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IC 8826 



ureau of Mines Information Circular/1980 



Materials Recycling 

An Overview of the Sixth Mineral 
Waste Utilization Symposium 



Compiled by S. A. Bortz and K. B. Higbie 




UNITED STATES DEPARTMENT OF THE INTERIOR 



9 " ' 

Information Circular 8826 



Materials Recycling 

An Overview of the Sixth Mineral 
Waste Utilization Symposium 



Compiled by S. A. Bortz and K. B. Higbie 




UNITED STATES DEPARTMENT OF THE INTERIOR 
Cecil D. Andrus, Secretary 

BUREAU OF MINES 

Lindsay D. Norman, Acting Director 



<M^ 




1> H ^ 



v • 



«* 



This publication has been cataloged as follows: 



Bortz, Seymour A 1922— 

Materials recycling: an overview of the sixth mineral waste 
utilization symposium. 

(Information circular « Bureau of Mines ; 8826) 
Supt. of Docs, no.: I 28.27:8826. 

1. Recycling (Waste, etc.)— Congresses. I. Higbie, Kenneth B., 
joint author. II. Mineral Waste Utilization Symposium, 6th, Chicago, 
1978- III. Title. IV. Series: United States. Bureau of Mines. Information 
circular ; 8826- 



TN295.U4 [TD794.5] 622s [604'.6] 80-607088 



PREFACE 

The United States, as a modern industrialized nation, is the product of 
constantly advancing technology. Our mobility, our affluence, and our high 
overall standard of living are manifestations of technological progress. So 
is solid waste pollution. 

Technology can and does create pollution. Fortunately, it can also be 
applied to control and abate this pollution. From an environmental stand- 
point, the handling, discharge, and conversion of solid waste are obviously 
of public concern, and in these days of energy shortage, we can no longer 
ignore the importance of solid wastes, no matter what form they take — 
industrial, mining, agricultural, or domestic. The objective of the Sixth 
Mineral Waste Utilization Symposium was to be of service to those who are 
sincerely concerned in both energy and environment, and who wish to share 
their views on the recycling and disposal of solid wastes. The symposium 
was attended by 126 persons, 18 of whom were from outside the United States. 

Recycling is an economic phenomenon. The extent to which a given mate- 
rial is recycled is a function of the values of so-called secondary materials 
in relation to so-called virgin materials . These relative values can change 
as a result of many factors, including changing technology, tax policies, 
transportation, and new applications. It was the theme of this symposium 
to look at both technical and economic factors, to describe progress over 
the last 10 years, to point out problems resulting from utilization of solid 
wastes, and to suggest new solutions to these problems. 



* 
* 

<* 






»3 



CONTENTS 



Page 



x 



Preface ,, 

Abstract 

Total resource recovery, by R. C. Kirby 2 

Mining and Mineral Wastes 

Comments on the utilization of mining and mineral wastes, by E. Aleshin. 10 
Utilizing recovered sulfur in construction materials, by W. C. McBee, 

T. A. Sullivan, and H. L. Fike 12 

Utilizing smelter slags at White Pine Copper Division, 

by J. F. Clarkson, R. H. Johnson, E. Siegal, and W. M. Vlasak 14 

Utilizing waste retorted oil shale for highway construction, 

by D. Y. Lee and C. A. Carradus 16 

Utilizing spent oil shale in preparing glass fiber and glass ceramics, 

by T. Horiuchi, T. Mizuno, C. H. Chung, and J. D. Mackenzie 17 

Abundance and recovery of sphalerite and fine coal from mine wastes in 

Illinois, by J. C. Cobb, J. M. Masters, C. Treworgy, and 

R. J. Helfinstine 18 

Utilizing Bayer process muds: problems and possibilities, 

by B. K. Parekh and W. M. Goldberger 20 

Construction industry efforts to utilize mining and metallurgical wastes, 

by R. J. Collins 25 

Iron recovery and glass fiber production from copper slag, 

by C . H . Chung , T . Mizuno , and J . D . Mackenzie 28 

Municipal Refuse 

Resource recovery for municipal solid waste disposal — an overview, 

by P . J . Cambourelis 31 

Albany-New York solid waste energy recovery system (ANSWERS) : City- 
state partnership in solid waste energy recovery returns profit to 
both, by P . F . Mahoney 35 

Direct incineration of municipal solid waste versus separation of 

combustibles, by S. L. Law, B. W. Haynes, and W. J. Campbell 36 

Preparing densified refuse-derived fuel on a pilot scale, by H. Alter 

and J . Arnold 39 

Aluminum scrap recovered from full-scale municipal refuse processing 

systems, by G. F. Bourcier and K. H. Dale 41 

Test results and application in commercial municipal solid waste plants, 

by C. Cederholm 43 

Progress in producing detinned steel from urban refuse magnetic 

fractions, by H. V. Makar and E. L. Gresh 46 

Monroe County resource recovery facility, by D. B. Spencer 50 

Promising applications for municipal incinerator residues, 

by R. J. Collins , 52 

Fiber recovery from municipal solid waste, by G. M. Savage, L. F. Diaz, 

and G. J. Trezek 54 

Recovery of glass from urban refuse by froth flotation, 

by J. H. Heginbotham 56 



IV 



CONTENTS — Continued 



Page 



Test procedures for determining the gross calorific value of refuse and 

refuse-derived fuels by oxygen bomb calorimetry, by D. R. Kirklin, 

D. J. Mitchell, J. Cohen, E. S. Domalski, and S. Abramowitz 61 

Operating economics of the City of Ames resource recovery system, 

by S . H. Russell and M. K. Wees 64 

Trommel processing of municipal solid waste prior to shredding, 

by J. F. Bernheisel, P. M. Bagalman, and W. S. Parker 67 

Upgrading products from raw refuse for marketing, by M. M. Cavanna, 

J. S. Almaraz, F. P. Cristobal, and H. G. Ramirez 68 

Utilizing processed incinerator residue as cover material for sanitary 

landfills, by R. E. Cummings 71 

Solid waste characterization for resource recovery design, 

by J. P. Woodyard and A. J. Klee 73 

Maryland Environmental Service-Baltimore County resource recovery 

facility, Texas, Md., by C. R. Willey and M. Bassin 76 

Impact — paper recycling versus supplemental fuel, by H. J. Perry 79 

New reclaiming process for waste papers, by K. Saitoh, N. Nishijima, 

and A . Kimura 81 

Industrial Wastes 

Recycling scrap — a decade of challenges and frustrations, by H. Ness.... 82 
Waste management strategy for major industries, by J. J. Emery 

and D . B . Matchett 86 

Iron and carbon recovery via the Reclaform process, by J. S. Young, Jr.. 89 
Recovery of zinc oxide from glavanizing wastes, by J. B. Stephenson, 

P. G. Barnard, and A. A. Cochran 91 

Recycling of potlining in the primary aluminum industry, 

by W. D. Balgord 93 

Powerplant fly ash as a source of alumina, by M. J. Murtha and G. Burnet 95 
A study of industrial waste materials exchanges operating in Europe and 

North America, by R. G. W. Laughlin and H. Mooij 96 

Beneficiation of steel plant waste oxides by rotary kiln processes, 

by H. Rausch and H. Serbent 98 

"CANMET" water recovery system for industrial effluents, by H. A. Hamza 

and N . E . Andersen 100 

Scrap Metal 

Overview, by H . Cutler 103 

The backlog of iron and steel discards in the United States, 

by H . Cutler 108 

Barriers to the use of secondary metals, by B. M. Sattin Ill 

Options for the collection and recovery of household appliance 

materials , by E . A . Kinne » 115 

Separation of nonferrous metals in automobile scrap by means of 

permanent magnets , by E . Schloemann 119 



V 



CONTENTS— Cont inued 

Page 

Characterization of scrap electronic equipment for resource recovery, 

by B. W. Dunning, Jr 122 

Progress in resource recovery in appliance manufacturing, 

by T. H. Goodgame and E. W. Hartung 123 

Recovery of cadmium from nickel-cadmium scrap batteries, by D. A. Wilson 126 

Miscellaneous 

Congressional and agency roles in resource recovery, by F. McManus 128 

ASTM Committee E-38 on Resource Recovery, by R. D. Vaughn 130 

An approach to energy attenuation of explosive wastes in processing 

equipment, by A. R. Nollet, E. T. Sherwin, and A. W. Madora 132 

Development of contingency plan standards for accidents with hazardous 

waste materials, by P. C. Knowles and R. C. Tucker 135 

Utilizing wastes and byproducts in Canadian construction, by J. J. Emery 139 
Powerplant ash utilization and energy conservation effects, 

by J. H. Faber 145 

Recycling metals: Processes and energy requirements, by C. L. Kusik, 

S. Malhotra, M. Mounier, K. Parameswaran, D. Kleinschmidt , 

and J . Milgrom 146 

Bureau de Recherches Geologiques et Minieres processes for resource 

recovery from French urban waste, by J. N. Gony and F. Clin 151 

Waste products to fertile soil — the combination of flue gas desulfuriza- 

tion sludges and fine coal refuse with municipal waste, by R. C. Freas 

and R. W. Briggs 155 



MATERIALS RECYCLING 
An Overview of the Sixth Mineral Waste Utilization Symposium 1 

Compiled by 
S. A. Bortz2 and K. B. HigbieS 



ABSTRACT 

This Bureau of Mines report reviews the information presented at the 
Sixth Mineral Waste Utilization Symposium cosponsored by the Bureau of Mines, 
U.S. Department of the Interior, and the IIT Research Institute. Environ- 
mental scientists and engineers from nine countries participated in the 
symposium, which was held May 2-3, 1978, at the Chicago campus of IIT 
Research Institute. The 56 papers presented on the reclamation and recycling 
of mining and mineral wastes, municipal solid waste, industrial wastes, and 
scrap metal are summarized herein. 



^he complete papers and additional bibliographic information can be found 
in the Proceedings of the Sixth Mineral Waste Utilixation Symposium pub- 
lished jointly by the U.S. Bureau of Mines and IIT Research Institute. 
Inquiries regarding individual papers should be directed to respective 
authors. Inquiries regarding the overall symposium should be directed 
to the U.S. Bureau of Mines, Director, Division of Mineral Resources 
Technology, Department of the Interior, Washington, D.C. 20241. Copies 
of the Proceedings of the Sixth Mineral Waste Utilization Symposium can 
be obtained by sending a check for $30 each to IIT Research Institute, 
P.O. Box 4963, Chicago, Illinois 60680. 

2 Senior engineering advisor, Materials Technology Division, IIT Research 
Institute, Chicago, 111. 

3 Deputy Director, Division of Research Center Operations, U.S. Bureau of 
Mines, Washington, D.C. 



TOTAL RESOURCE RECOVERY 

by 
R. C. Kirby 



Introduction 

Nature concentrated her riches in complex deposits around the world. It 
is our challenge to discover and use them wisely. True conservation means 
maximum employment of our resources- — and minimum waste. Total resource recov- 
ery implies the utilization of all materials extracted from the ground. Con- 
sider, for the moment, the Mascot mines in Jefferson City, Tenn. There, the 
deposit contains 4 pet zinc and over 95 pet limestone. The ore is mined and 
concentrated for zinc recovery. The tailings from flotation are dried and 
sold as agricultural lime. The float-sink reject is sold as crushed stone. 
The mine and mill recover, for economic use, nearly all of the rock extracted 
from the Earth's crust. Total resource recovery is approached. 

Without total recovery we will have to find a way to renew nonrenewable 
resources. Part of the answer lies in secondary resource recovery and mineral 
waste utilization. We are meeting at the sixth symposium in this series 
cosponsored by the Bureau of Mines to address part of the problem. At this 
symposium we should review not only what we have learned in the last 2 years, 
but also what has been learned in the 10 years since the first symposium. 
Where have we made progress? Where have we failed? And what can we do to 
more closely approach total resource recovery? We hope that this symposium 
will serve as a forum to answer these questions. 

To set the stage for this look backward as well as forward, I want to 
examine the current state of resource recovery technology, technology develop- 
ment needs, and appropriate roles for various segments of society in meeting 
those needs. 

The Problem Defined 

In meeting society's needs for metals, minerals, and fuels, the extrac- 
tive and basic materials industries have had to treat progressively lower 
grade ores. The average copper ore, at the turn of the century, was 3 pet 
copper; Today, it is less than 1 pet. Iron ore, at the turn of the century, 
was so rich that it needed only to be mined and shipped to the blast furnace. 
Further processing was unnecessary. Benef iciation began as washing and 
screening, and only recently has it begun to include concentration and indura- 
tion steps. 

The demand for more materials, coupled with the necessity for treating 
lower grade ores, has resulted in an inevitable trend — the production of 

director, Division of Mineral Resources Technology, Bureau of Mines, 
Washington, D.C. 



increasing volumes of solid, liquid, and gaseous wastes. The extent; to which 
these wastes are made into usable byproducts represents progress toward total 
resource recovery. The extent to which they are discarded as useless waste — 
or even harmful waste — represents the remaining problem. Table 1 quantifies 
the mineral industry solid waste problem in 1975. Total mineral waste genera- 
tion from nonfuel minerals now exceeds 2 billion tons per year (3) 2 and 
exceeds municipal waste generation by a factor of more than 15. 

TABLE 1. - Solid wastes generated by the mineral industries 



Industry 



Copper 

Phosphate rock. 
Iron and steel. 

Lead-zinc 

Aluminum 

Other 



Bulk weight of waste, 
million tons per year 



960 
350 
420 
23 
15 
380 



Source: Morning (3). 

Effluents and emissions, such as acid mine waters and sulfur dioxide, 
also create problems. Analysis at each major step in the materials system 
is warranted. 



Mining and Concentrating 

Mining and concentrating produce the bulk of the wastes generated by the 
minerals industry: Gangue, tailings, and mine water are the principal prob- 
lems. These problems have been addressed over many decades with research, 
development, and commercialization. Several examples of successful resource 
recovery merit mention. 

Recovery of copper by cementation, it should be remembered, began as an 
approach to more complete resource recovery. It was first practiced in the 
Spanish copper mines during the 16th century. It emerged in this country as 
a waste-rock-plus-ferrous-waste system. At Utah Copper, it incorporated a 
third waste — acid mine water. Today the Utah Copper Division of Kennecott 
Copper pumps about 60 million gallons of sulfuric acid solution per day over 
strip mine waste rock at the Bingham pit. This acid is derived from the iron 
and copper sulfide residues contacted by the waste water. The copper content 
of a very few pounds per ton of waste rock is dissolved in the acid solution. 
It is then recovered as cement copper by circulation of the leach solution 
over "tin" cans where the iron precipitates the copper. Today cementation is 
used throughout most of the U.S. copper industry and accounts for about 10 pet 
of our domestic production. 

Mine water can also be used. During 30 years of its operating life, 
Copper Range Co.'s Champion mine supplied water to the city of Houghton, Mich. 



Underlined numbers in parentheses refer to items in the list of references 
at the end of the individual papers. 



When the mine was closed, that city acquired control of the water. The 
waste outlived the primary product (1) . 

Examples of similar successes abound— turning broken marble slabs into 
ground whiteners for paint and plastics applications, using chert from 
Missouri lead mining for road construction, and extracting uranium from mine 
waste or phosphate processing streams are three of the many cases. 

To illustrate typical problems that remain, phosphate slimes continue to 
accumulate. Present industrial practice permits recovery of only about two- 
thirds of the phosphate value. The remainder is lost in the beneficiation 
waste, especially the Florida clay slimes. Solids in the slimes remain in 
suspension and do not settle out, resulting in serious environmental problems. 
The Bureau of Mines is working on a direct acid digestion process for Florida 
ore that will increase phosphate recovery, as phosphoric acid, to over 90 pet 
and produce a filter cake that will get around slimes storage problems. If 
such research leads to commercial practice, it will extend our phosphate 
reserves significantly and simultaneously reduce the environmental risks of 
phosphate processing. In addition, other Bureau research and development is 
aimed at recovering phosphate from existing slime ponds or from newly formed 
slimes. Slimes would still be formed during beneficiation of phosphate ore 
for uses other than acid production. 

Technology is needed not only for phosphate but also for the reuse of 
vast quantities of finely ground material which, at present, still accumulates 
from processing other ores. In the near term, we must improve tailings 
stabilization— and much work is now going on. In the mid and long term, some 
of these materials must emerge as useful byproducts to improve total resource 
recovery. The fundamental need, then, is for technologies that will convert 
these materials into usable objects— at a cost that makes such processes 
economically attractive. 

It has been our experience that, when processes emerge that are environ- 
mentally attractive and economically acceptable, they will be adopted. Cer- 
tainly widespread use of copper cementation demonstrates this point. The 
beginnings of a byproduct uranium industry also illustrate that adoption does 
occur. The keys remain, however: A combination of profit potential and regu- 
lation motivates industry to adpot new practices— if conditions are favorable— 
or constrains industry if it means hindering services to, and performance in, 
the economy. 

Processing and Refining 

Ore concentrates, when smelted and refined, yield valuable metals. They 
also yield a variety of slags, drosses, and off gases. Slags have found a 
variety of uses— increasing the resources recovered from concentrates. Some 
drosses are also recycled. Off gases, notably S0 2 , are targets for 
consideration. 

Iron and steel slag offers an instructive example of resource recovery. 
Tens of millions of tons of blast and steel furnace slags accumulated until 



after World War II. Modest quantities were used in road construction, cement, 
and mineral wool. Then a vigorous marketing program coupled with an expanding 
construction economy solved this disposal problem. Today almost 30 million 
tons of blast furnace and 10 million tons of steel furnace slags are marketed 
annually for use in highway and airport construction, railroad ballast, bitu- 
minous concrete construction, and cement production. Slags now sell for $4 to 
$6 per ton. 

Some 6.9 million tons of iron and steel slag are produced each year in 
France, and 3.3 million tons are sold to cement manufacturers there. This 
slag achieves 75 pet energy savings when used in portland cement (2) . In 
South Africa, half a million tons of Slagment 3 is sold. Sales of Slagment 
could be higher if more iron and steel slags were available. In Great Britain, 
a similar product named Cemsave is marketed (2) . 

Clearly, slags from ferrous metal have been found useful and salable. 
Similarly, foundry dusts have become valuable byproducts — particularly as soil 
conditioners. These are examples of resource recovery in its best sense — con- 
verting useless wastes into economically sound byproducts. Problems remain in 
this area, however, which can and should be addressed by research. 

Copper smelter slag, although useful in the same manner as steel slag, 
contains 25 to 35 pet iron. This iron would be useful in the cementation 
process if it could be recovered in shapes offering the desirable surface- 
area-to-mass ratio exhibited by tin cans . We have investigated this problem 
and devised a method on a small scale. If the method is adopted, the economic 
value of smelter slag could be upgraded. 

Bureau of Mines research projects are developing methods for recovering 
chromium and nickel from ferroalloy flue dusts, stainless steel furnace dusts, 
mill scale, foundry sand, chrome-bearing refractories, and other materials. 
Table 2 presents the amounts of these strategic and critical elements that 
are available as wastes. Success in this effort, if followed by commercial 
acceptance, could make a significant impact on import dependence. 

Emissions, particularly SO2, present serious problems for smelters. 
Currently, many smelters recover some of the sulfur dioxide in the form of 
sulfuric acid. This acid is used within the plant or sold. Smelters, how- 
ever, can recover far more sulfuric acid than they or their customers can 
possibly use. Thus, at present, there is a significant waste of sulfur which 
could be put to useful purposes, such as extending petroleum-based asphalt. 
With the total resource recovery concept in mind, the Bureau pioneered the 
citrate process for removing sulfur from stack gas and recovering it in a 
storable, transportable, and more useful form as elemental sulfur. The recent 
pilot plant tests at the Bunker Hill smelter demonstrated the technical sound- 
less of this approach. Scale-up of the process, for application to the more 
dilute stack gases emitted by coal-burning powerplants, is now underway at the 
St. Joe Mineral coal-fired powerplant outside Pittsburgh. 

3 Reference to specific trade names or equipment does not imply endorsement by 
the Bureau of Mines . 



TABLE 2. - Chromium and nickel in wastes, tons per year 



Source 



Ni 



Ferroalloy: 

Flue dusts 

Slags 

Stainless steel: 

Furnace dus t s * 

Centerless grinding swarfs 

Mill scale 

Pickle liquid 

Slags 

Electrochemical and electrical discharge machining sludges . . . 

Foundry sand 

Refractories 

Etching 

Plating 

Catalysts 

Chromate and dichromate production 

Leather tanning 

Paint pigment 

Textiles 

Phosphating metal-coating wastes 

NiCd batteries 



NAp 
NAp 

700 
600 
1,000 
800 
250 
2,600 
NAp 
NAp 
1,000 
3,900 
2,500 
NAp 
NAp 
NAp 
NAp 
10-20 
C 1 ) 



NAp Not applicable. 
1 Unknown. 

Because establishments in the private sector must remain profitable if 
they are to supply the economy with both products and jobs, financial incen- 
tives and regulatory actions often provide them with stimuli for action. 
Because the Federal Government promulgates regulations concerning waste dis- 
posal and environmental protection, it has the responsibility to help industry 
find economically sensible solutions. The discharging of that responsibility 
comes through technical research — with the aid of academic institutions and 
the active cooperation of industry. 

Product Manufacturing 

The myriad industrial processes that give us final products all produce 
scrap. Most of this is generated as prompt industrial scrap and forms the 
foundation for the $4 billion secondary materials industry. The manufacturing 
community understands the value of its residues and practices recycling more 
than any other sector of the economy. Its high resource recovery rate is 
closely related to a recognition of the economic value of these production 
residues . 



Prompt industrial scrap has the most desirable characteristics (other 
than home scrap). It is of known chemical composition. Few, if any, unpleas- 
ant surprises result from its use. It is generally in a metallic state, which 
offers energy conservation over processing primary minerals. Capital costs 
for secondary smelter installations, on an annual capacity basis, are 
significantly lower than those for primary smelters. 



The technologies for using these materials are well developed. The elec- 
tric furnace and minimill for recovering ferrous metals, the secondary smelt- 
ers for aluminum, copper, and other nonferrous metals, and the glass furnace 
charged with 10 to 20 pet cullet are well established. 

What is less well established is a smooth economic pattern to stabilize 
the flow of prompt scrap. Because this scrap provides the marginal increment 
of raw materials supply necessary for meeting relatively strong levels of 
demand, its use fluctuates widely. Fortune Magazine dubbed 1974 as "the 
tinsel days" for scrap dealers — whose products were in extreme demand. The 
year 1975 could be considered the "tattered days" for the steel mills, and 
the nonferrous scrap consumers also slashed their purchases drastically. 

A useful solution to this problem — on a total basis — may be the develop- 
ment of more technologies where scrap is the basic raw material rather than a 
marginal increment of supply. Electric furnaces offer this potential for 
steelmaking — particularly in the minimills . In larger electric furnace 
establishments, scrap must compete with prereduced iron pellets. The second- 
ary smelters of nonferrous metals, which now recycle their own drosses as well 
as those from primary smelters, are closer to having scrap as the basic raw 
material . 

Obsolete Wastes 

After products have been made and used, they either wear out or become 
obsolete. They are discarded. In addition to the 135 million tons of munici- 
pal solid waste discarded each year, batteries and some 9 million automobiles 
are junked. Stoves and other household appliances are discarded. Buildings 
are torn down. The discards of a modern society continue to pile up. 

These residues, rejects from our materials system, have commanded the 
bulk of society's attention in the waste processing area. Table 3 presents 
municipal processing plants now on-stream. Clearly, such processes have 
become commercial. And although "bugs" and "glitches" exist, we know how to 
sort trash into useful components . 

In the automobile area, the progress since 1960 has been amazing. The 
widespread use of shredding technology increased junk automobile recycling to 
a level of 90 pet. The shredder improved the quality of the ferrous scrap and 
made it more useful to steelmakers. At the turn of this decade, Huron Valley 
Steel Corp. developed a sink-float system to handle the nonferrous material 
from auto shredders. Today, Huron recovers 25,000 tons each of zinc and 
aluminum annually. 

Most lead from scrap auto batteries is reclaimed and recycled by several 
other firms. Nearly one-half of our annual consumption of lead is met from 
secondary sources. Despite this progress, technical problems and opportuni- 
ties in the obsolete scrap area are significant. 

An example is the plastics in automobiles. This use of plastics is 
increasing steadily. By 1980, the average car may contain 400 pounds of 



plastics. We are also working on methods to segregate individual plastics 
economically. This project, being performed in cooperation with Ford and 
General Motors, has already achieved a promising method for isolating poly- 
ur ethane foam. Such successes will help achieve systems where plastics are 
recycled — thus saving valuable petroleum and natural gas feedstocks. These 
issues must be addressed if we are to approach total resource recovery. 

TABLE 3. - Municipal refuse recycling plants 



Operational 


Size, 
tpd 


Committed or being built 


Size, 
tpd 


South Charleston, W. Va.. 


200 

200 

1,500 

1,600 

1,600 

400 

720 

1,200 

360 

240 

300 

650 

150 

1,200 




200 
2,000 






1,000 
1,000 
1,800 
2,000 
100 
500 


Norfolk, Va 


2,200 
1,000 




Albany, N.Y 


500 
750 






400 


East Bridgewater, Mass... 








10,320 


13,450 



Society motivates moves in this area of resource recovery from wastes, 
and advances are coming rapidly. There is sufficient economic and legal 
incentive to continue this thrust. What appears as an unmet need is the 
technology to use some of the marginal commodities which emerge from the 
solid waste stream. 



Technology Status 

The systems for classifying and separating many product and waste streams 
are well developed. This holds true at most levels of the materials- 
processing system. Minor problems and exceptions will always exist, but they 
are not sufficient to impede meeting our raw material needs. 

Numerous systems also exist, and are well entrenched in the U.S. commer- 
cial system, to use particular waste products. These include copper cementa- 
tion, slag usage, secondary smelting of prompt industrial scrap, and the 
recovery and reuse of metallic elements in junk automobiles. It is popular 
to say that all resource recovery technology began in the 1960's or — stretch- 
ing the point — those ancient years, the 1950 's. One must pause for a moment, 
however, and consider that nearly 4,000 years ago, Europe's metals trade was 
reorganized to insure more complete collection, recovery, and reutilization 
of bronze scrap. Early American settlers and pioneers had to practice recyc- 
ling. For instance, old buildings were burned to recover nails. Over a 
century ago, Charles Dickens was writing about reclaiming values from 



"dust heaps" in his book "Hard Times." That those dust heaps could be given 
as dowries makes a salient point: technologies had developed in response to 
economic incentive. 

Technology Needs 

To say that technology has emerged does not imply that such technology 
is totally adequate. There are both short- and long-term needs that must be 
met if we are to chart a course toward total resource recovery. 

In the near term, we must conceive and create more product development 
and utilization technologies . What is needed is a clear identification and 
ordering of priorities for product utilization technologies that can be 
developed by research. 

Over the longer term we must seek out systems to evaluate and develop as 
many "ore bodies" as possible from this total resource recovery perspective. 

Uses for the separated fractions must be developed. Certainly, each new 
waste-processing operation must be based not on a national perspective, but 
rather on the marketability of what is separated and recovered. One direction 
that research and development should take is to assure the usefulness and 
applicability of materials to reuse in the best form. This is part of the 
path to renewing nonrenewable resources . 

References 

1. Bingham, E. R. Waste Utilization in the Copper Industry. Proc. 1st 

Mineral Waste Utilization Symp. ,cosponsored by BuMines and IIT Research 
Institute, Chicago, 111., Mar. 27-28, 1968, p. 74. 

2. Emery, J. J. Slags. Proc. 5 th Mineral Waste Utilization Symp. , 

cosponsored by BuMines and IIT Research Institute, Chicago, 111., 
Apr. 13-14, 1976, p. 292. 

3. Morning, J. L. Mining and Quarrying Trends in the Metal and Nonmetal 

Industries. BuMines Minerals Yearbook 1975, v. 1, 1977, pp. 71-124. 



10 



MINING AND MINERAL WASTES 

COMMENTS ON THE UTILIZATION OF MINING AND MINERAL WASTES 

by 
E. Aleshin 1 



The present accumulation of mining wastes in the United States amounts to 
over 360,000 tons per day. In the past a total of 23 billion tons has been 
amassed, and in the future waste will accumulate at a far greater rate. 
Examples of accumulated quantities and estimated annual production are shown 
in table 1. 



TABLE 1. - Estimated quantities of select mining wastes 



Industry 



Copper. . . 
Taconite. 
Phosphate, 
Iron ore. , 

Gold , 

Uranium. . , 

Lead 

Zinc 

Aluminum. , 



Waste rock, 
million tons 
per year 



624 

100 

230 

27 

15 

156 

0.5 

.9 

NA 



Mill tailings, 
million tons 



Annual 



234 

109 

l 54 

27 

5 

5.8 

8 

7.2 

5 



Accumulated 



7,700 
3,600 
2 907 
730 
450 
110 
180 
180 
NA 



NA Not available. 
Includes both phosphate slimes and phosphogypsum. 
Includes an estimated 136 million tons of phosphogypsum. 

Source: Clifton, J. R., P. W. Brown, and G. Frohnsdorff. 
Survey of Uses of Waste Materials in Construction 
in the United States. National Bureau of Standards 
NBSIR 77-1244, 1977. 

Waste rock, which comprises the largest volume of mining wastes, is used 
as concrete aggregate, mine backfill, subbase, and bituminous paving aggre- 
gate. However, compared with the output, very little is utilized. 

Coarse mill tailings are stockpiled or put to the same kind of uses as 
waste rock. Finely divided tailings are piled or stored in* ponds. Again, 
very little is put to use. Taconite wastes, for example, are used in mine 
roadways; dolomite from zinc ore processing is used as a source of lime in 
agriculture. Red muds are settled in ponds; although the alkaline solution 



IIT Research Institute, Chicago, 111. (now with PEDCO Environmental, 
Cincinnati, Ohio) . 



11 



is decanted for reuse; the solids are not used extensively. Again, che rate 
of accumulation far exceeds the rate of use. 

Much productive research has been performed to show that waste resources 
can be made into products with satisfactory engineering properties, thus 
demonstrating that some of these materials have potential in the marketplace. 
However, very little of this effort has actually resulted in commercialization. 

The mining and milling industry produces the greatest volume of unused 
inorganic wastes, and a greater effort must be made to produce usable products 
from a larger portion of these wastes. Studies should be initiated to deter- 
mine the most promising potential uses for mining and mineral wastes, and 
preliminary economic and environmental analyses should be performed. Research 
must then begin to develop and improve the engineering properties for the most 
promising materials . 

A number of impediments must be overcome, not the least of which are poor 
understanding of waste resources by the user (be it manufacturer or ultimate 
consumer), lack of material and performance standards, and in some instances 
the cost advantage afforded by some virgin raw materials . 

Recognition of these and other impediments and a greater research and 
development effort by both government and industry will result in increased 
resources, improvement of the environment, and conservation of energy. 



12 



UTILIZING RECOVERED SULFUR IN CONSTRUCTION MATERIALS 

by 
W. C. McBee, 1 T. A. Sullivan, 2 and H. L. Fike 3 



Sulfur is unique among our mineral resources in that it is one of the few 
minerals that will be in abundant supply in the future. The Bureau of Mines 
forecasts potential production of coproduct sulfur in the United States to 
total 45 million long tons per year by the year 2000. This sulfur will be 
recovered from the processing of petroleum, natural gas, coal, and other fuels 
as well as from smelter gases. During the same year the demand for sulfur is 
forecast to total only 23 million long tons. Thus, if only half the potential 
sulfur is recovered, U.S. sulfur needs could be supplied without any produc- 
tion from primary sources. Current projections indicate that by the year 
1985, domestic production will exceed domestic demand by 1.5 million long 
tons. For this reason, various industry, government, and university groups 
have initiated research efforts to develop new uses for sulfur. 

Sulfur' s unique properties permit it to be utilized in construction 
materials either as a structuring agent, in which it plays the role of the 
aggregate, or as a binder to hold the materials together, or both. As a 
result, there has been an increase in research activities to use this 
versatile element in construction materials. 

Utilization in construction offers the most practical approach to new, 
large-scale uses for sulfur. Sulfur can be used as a direct substitute for 
asphaltic (4^5_) and portland cement (3) and for mineral aggregates (8-9) . 
There has also been development of sulfur foams (1, 6) , mortars (2) , spray 
coatings (7) and surface-bonding materials (7) . 



Metallurgist, Boulder City Metallurgy Engineering Laboratory, Bureau of 

Mines, Boulder City, Nev. 
Research chemist, Boulder City Metallurgy Engineering Laboratory, Bureau of 

Mines, Boulder City, Nev. 
3 Director of Industrial Research, Sulphur Institute, Washington, D.C. 



13 



References 

1. Hodgson, G. W. How To Make Foamed Sulfur. Oilweek, June 4, 1962, p. 32. 

2. Hubbard, S. J. Feasibility Study of Masonry Systems Utilizing Surface- 
Bond Materials. U.S. Dept. Army, Rept. 4-43, 1966, pp. 20-22, 33-35. 

3. Malhotra, V. M. Mechanical Properties and Freeze-Thaw Resistance of 
Sulfur Concrete. Canada Dept. of Energy, Mines and Resources, Mines 
Branch Rept. IR 73-18, 1973, 30 pp. 

4. McBee. W. C, D. Saylak, T. A. Sullivan and R. W. Barrett. Sulfur as a 
Partial Replacement for Asphalt in Bituminous Pavements. Ch. in New 
Horizons in Construction Materials. Envo Publishing Co., Lehigh Valley, 
Pa., 1976, pp. 345-362. 

5. McBee, W. C, and T. A. Sullivan. Sulfur Utilization in Asphalt Paving 
Materials. Adv. Chem. Ser., v. 165, 1978, pp. 135-160. 

6. Paulson, J. E., M. Simic, J. W. Ankera, and R. W. Campbell. Use of Sulfur 
Composites as Protective Coatings and Construction Materials. Adv. 
Chem. Ser., v. 165, 1978, pp. 215-226. 

7. Pickering, I. G., J. A. Watson, J. M. Dale, and A. C. Ludwig. A Sprayable 
Sulfur Coating for Protection of Concrete Leaching Vats. Proc. 78th 
Nat. Meeting, AICHE, Aug. 18-21, 1974, Salt Lake City, Utah. 

8. Saylak, D., B. M. Gallaway, and H. Akmad. Beneficial Use of Sulfur in 
Asphalt Pavements. Ad. Chem. Ser., v. 140, 1975, pp. 102-129. 

9. Sullivan, T. A., W. C. McBee, and W. C. Rasmussen. Studies of Sand- 
Sulfur-Asphalt Paving Materials. BuMines RI 8087, 1975, 30 pp. 



14 



UTILIZING SMELTER SLAGS AT WHITE PINE COPPER DIVISION 

by 

J. F. Clarkson, 1 R. H. Johnson, 2 E. Siegal, 2 
and W. M. Vlasak 3 



The White Pine Copper Division has been utilizing the discarded reverber- 
atory furnace slag from its smelter in a variety of ways over the past 6 years, 
The smelter started operation in 1955 and by 1974 had produced over 2 million 
tons of slag. The long-term average composition of our raw reverberatory fur- 
nace slag is given in table 1. However, this average composition is mislead- 
ing as it is known that the dump contains appreciable tonnages of slag which 
deviate significantly from the long-term average, particularly with respect to 
copper content. Copper losses in the slag occur for many reasons: 

1. Both the molten copper matte (Cu-Fe sulfides) formed in the smelting 
process and the copper contained in the converter slag returned to the reverb- 
eratory furnace form small droplets which must settle through the slag to col- 
lect in the heavier matte pool under the slag layer. The White Pine reverber- 
atory furnace slag is very viscous due to the high Si02~FeO ratio, and the 
smallest copper-bearing droplets become entrained in the slag and are dis- 
carded with the slag before they can settle out . 

2. If small amounts of nickel get into our final refined copper, it will 
not meet the guaranteed 100 pet electrical conductivity. When excessive 
nickel contaminant gets into the smelter circuit, special fire-refining tech- 
niques are used to keep the copper clean. These special techniques result in 
high-copper converter slags being reintroduced into the reverberatory furnace, 
which exaggerates the losses outlined in 1 above. 

3. Toward the end of any furnace campaign, the furnace bottom builds up 
randomly forming dams, trapping small pockets of liquid matte. It then 
becomes difficult to get a good slag skim without accidentally taking some of 
the matte. 

4. There is a strong correlation between copper slag losses and the 
resmelting of plant secondaries (foul slag, ladle shells, cleanup, etc.). 
About 4 pet of the reverberatory furnace charge is normally secondary materi- 
als, but there are periods when excess furnace capacity is available and is 
used to reduce the inventory of secondaries. A definite increase in slag 
copper assays can be seen when secondaries form as much as 6 pet of the 
furnace charge. 

director of Metallurgical Research, Copper Range Co., White Pine Copper Div., 

White Pine, Mich. 
Senior research engineer, Copper Range Co., White Pine Copper Div., 

White Pine, Mich. 
Concentrator metallurgist, Copper Range Co., White Pine Copper Div., 

White Pine, Mich. 



15 



TABLE 1. - Average composition of White Pine reverberatory slag 



Composition 


Pet 


Composition 


Pet 


Cu 


1.35 
42 
12 
16 


CaO 


20 


Si0 2 , 


K 2 0. . , 


3 


AloOq 


2 


FeO 






2 









The very first exploratory studies on copper recovery from the reverberatory 
slag were done in 1967 at Michigan Technological University using crushing, grind- 
ing, and froth flotation. After receiving their results and noting the required 
fine grind, high energy consumption, and abrasive nature of the slag, the White Pine 
Metallurgical Research Department decided to try gravity concentration before con- 
tinuing in the direction of froth flotation copper recovery. Metallurgical evalu- 
ation in the laboratory and pilot plant testing in 1968-69 determined that enough 
copper could be recovered from the reverberatory furnace slag to justify investment 
in a heavy-media plant . 

Construction of the heavy-media plant began in late 1970 and was completed in 
May 1971. It was designed for seasonal operation, generally April through November, 
Because of plant startup problems, an industrywide strike, and modifications to the 
circuit, the plant did not start full operation until April 1972. The heavy-media 
plant operated seasonally in 1972, 1973, and 1974, treating 1.99 million tons of 
reverberatory slag to recover 10 million pounds of copper. 

In addition to producing a heavy-media copper concentrate for the smelter, the 
plant made a 1-inch by 4-mesh tailing having approximately 3.0 specific gravity 
(3.0 float), a 1-inch by 4-mesh product having approximately 3.4 specific gravity 
(3.4 float), and a 4-mesh by jig tailings; about 1 pet of the plant's feed tonnage 
reported as minus 100-mesh slime tails . 



The 3.0 float and jig tails made an excellent aggregate for a variety of 
construction purposes including roadbase, drain fields, railroad ballast, concrete, 
and blacktop roads. 

The 3,4 float middling material assays 1.34 pet copper, and this was stock- 
piled for possible future treatment to recover the contained copper. Laboratory 
grinding and flotation studies and short test runs in the White Pine concentrator 
demonstrated that the copper in the 3.4 float could be profitably recovered by 
blending the 3.4 float with the mine ore for conventional milling and froth flota- 
tion. This method has been practiced for the last 2 years with copper sales dic- 
tating the daily treatment rate (up to 3,000 short tons per day of 3.4 float into 
the concentrator). Copper can also be recovered in this manner from jig tails and 
raw reverberatory slag. 

White Pine's recent slag utilization efforts have taken off in a new direction, 
For the past 1^ years, sized dump slag has been sold to mineral wool insulation 
manufacturers at rates up to 1,000 tons per week. The reverberatory dump slag is 
first sized at minus 5 plus 1% inches and then shipped by rail to the customers. 
The slag is mixed by the manufacturer with other materials to adjust the overall 
composition and melted with coke in a cupola furnace. The molten stream issuing 
from the furnace is spun into mineral wool to be used as insulation. 



16 



UTILIZING WASTE RETORTED OIL SHALE FOR HIGHWAY CONSTRUCTION 

by 
D. Y. Lee 1 and C. A. Carradus 2 



To meet the future energy demand, in view of the threat imposed by • the shortage 
of petroleum and the certainty of its eventual depletion, the United States has 
expended considerable effort developing oil shale technology in recent years. 

Although serious emphasis has been given to the in situ retorting of oil shale, 
major developmental activity has been directed mainly toward the mining-retorting 
approach to shale oil production, near the oil shale deposits of the Green River 
Formation in Colorado, Utah, and Wyoming. 

A major and immediate problem in deriving energy from shale oil, aside from 
costs, technology, and material and manpower, is the disposal of waste (spent shale), 
The spent shale will be 80 to 85 pet of the raw shale in weight and will occupy a 
volume up to 50 pet greater than the shale before oil is extracted from it (1) . 
Because of the large increase in bulk volume of the solid residue, the mine cannot 
accommodate all of the waste, and a significant portion will have to be disposed of 
aboveground . 

Useful deposits of oil shale in the Green River Formation alone are estimated 
to contain about 2 trillion barrels of crude oil equivalence (5) . Extracting this 
would result in an extraordinarily large volume of waste. For example, the produc- 
tion of 100,000 barrels of oil will result in about 150,000 tons of shale residue. 
Based on the estimated, slightly compacted density of the shale residue of 90 pounds 
per cubic foot, complete extraction of the 2 trillion barrels of oil would result in 
a waste pile of about 1,400 million acre-feet. While attention and study are being 
given to processed shale revegetation, development of stable dumps, and prevention 
of excessive blowing of dust, the most desirable solution of the disposal problem is 
in the form of waste utilization. There is the possibility of using the shale resi- 
due from retorting plants as a road construction material, specifically for use as 
fill material, as stabilized base and subbase, and as aggregate in both portland 
cement (3-4) and asphalt cement concrete (2) . 

References 

1. Adelman, M., et al. Energy Self-Suff iciency : An Economic Evaluation. Tech. 

Rev., v. 76, No. 6, 1974, p. 23. 

2. Asphalt Institute. Mix Design Methods for Asphalt Concrete and Other Hot-Mix 

Types-MS-2. College Park, Md., 1974. 

3. Portland Cement Association. Soil-Cement Laboratory Handbook. Skokie, 111., 

1971. 

4. Woods, K. B., D. S. Berry and W. H. Goetz. Highway Engineering Handbook. 

McGraw-Hill Book Co., Inc., New York, 1960. 

5. Yen, T. F. Science and Technology of Oil Shale. Ann Arbor Publishers, 

Ann Arbor, Mich., 1976. 

lAssociate professor, Department of Civil Engineering, Engineering Research 

Institute, Iowa State University, Ames, Iowa. 
Graduate research assistant, Department of Civil Engineering, Engineering Research 
Institute, Iowa State University, Ames, Iowa. 



17 



UTILIZING SPENT OIL SHALE IN PREPARING GLASS FIBER AND GLASS CERAMICS 

by 
T. Horiuchi, 1 T. Mizuno, 1 C. H. Chung, 1 and J. D. Mackenzie 1 



Oil shale deposits in the United States exist in at least 30 States 05) . 
The largest and richest oil shale deposits in Colorado, Utah, and Wyoming are 
well known (1 , _3-4) . 

The average oil in Wyoming contains about 86 pet inorganic solids and 
14 pet organic materials with practically no absorbed water (2) . This type 
of shale will yield approximately 25 gallons of oil per ton. 

After the oil has been extracted, the disposal of the inorganic residue 
becomes a problem. Such spent oil shales are easily meltable and can be 
formed into glass without the addition of other raw materials to the batch (6) . 
The glass is easily converted to a fine-grained glass ceramic of superior 
properties (2) • 

References 

1. Duncan, D. C, and V. E. Swanson. Organic Rich Shale of the United States 

and World Land Areas. U.S. Geol. Survey Circ. 523, 1965. 

2. Jaffe, F. C. Oil Shale, Part II. Colo. Sch. Mines Miner. Ind. Bull., 

v. 5, No. 3, 1962. 

3. Prien, C. H. Oil Shale and Shale Oil. Oil Shale and Cannel Coal, v. 2, 

1951, pp. 399-418. 

4. . Current Status of U.S. Oil Shale Technology. Ind. and Eng. Chem., 

v. 56, No. 9, 1964, pp. 32-40. 

5. Rubel, A. C. Shale Oil — As a Future Energy Resource. Mines Magazine, 

v. 45, No. 10, 1955, pp. 72-76. 

6. Shelestak, L. J., R. A. Chavez, J. D. Mackenzie, and B. Dunn. Glasses and 

Glass-Ceramics From Naturally Occurring Ca0-Mg0-Al 2 0g-Si0 2 Materials (I) 
J. Non-Crystalline Solids, v. 27, 1978, pp. 83-97. 

7. . Glasses and Glass-Ceramics From Naturally Occurring CaO-MgO- 

Al 2 3 -Si0 2 Materials (II). J. Non-Crystalline Solids, v. 27, 1978, 
pp. 83-97. 



•'•All of the authors are with the Materials Department, School of Engineering 
and Applied Science, University of California at Los Angeles, Los Angeles, 
Calif. 



18 



ABUNDANCE AND RECOVERY OF SPHALERITE AND FINE COAL 
FROM MINE WASTES IN ILLINOIS 

by 

J. C. Cobb, 1 J. M. Masters, 2 C. Treworgy, 3 
and R. J. Helf ens tine 4 



Resource investigations of zinc in sphalerite-bearing coals in west- 
central Illinois show that the in situ zinc content of three coals mined 
ranges from 0.05 to 0.09 pet. The highest concentrations of zinc, up to 0.5 
pet, occur locally in disturbed areas of the coalbeds characterized by faults, 
slips, fractures, and clastic intrusions. Undisturbed portions of the coal 
usually contain less than 0.005 pet zinc. 

Zinc is present in the coal as a sulfide mineral, sphalerite (ZnS with 
up to 1 pet cadmium). Sphalerite occurs as fillings in fractures, cleats, and 
faults, and as crystal aggregates in clastic dikes which intrude the coals. 
The occurrence of sphalerite in coals and the relative ease with which the 
sphalerite can be reduced in the coal by specific gravity techniques is dis- 
cussed by Hatch, Gluskoter, and Lindhal (1), who speculated that recoverable 
quantities of sphalerite could be present in some existing coal refuse 
deposits. 

The west-central Illinois mining district (Fulton, Knox, Peoria, and 
Stark Counties) has an estimated coal resource of 7,500 million tons (3) 
occurring in three seams: the Colchester (No. 2), Springfield (No. 5), and 
Herrin (No. 6). With a zinc concentration from 0.05 to 0.09 pet, the coals 
in this area contain several million tons of zinc, an amount equal to that of 
some zinc mining districts. 

The annual raw coal production from this area is about 10 million tons. 
This raw coal is crushed, washed, and screened in preparation processes. The 
coarse-grained refuse is hauled to gob piles, and the fine-grained refuse is 
slurried and discharged into impoundments . A survey of surface-mined land in 
Illinois (2) lists 1,018 acres of uncovered slurry deposits and 858 acres of 
uncovered gob deposits in the west-central Illinois district. 

Random sampling of slurry and gob deposits from different mines in the 
area shows the concentration of sphalerite in refuse (tables 1 and 2) . The 
zinc content of these gob samples ranges from 0.001 to 0.6 pet, and that of 
slurry samples is 0.001 to 2.3 pet. Table 3 shows the zinc content of washed 
coal to range from 0.007 to 0.025 pet. 



Research associate, Illinois State Geological Survey, Urbana, 111. 
2 Assistant geologist, Illinois State Geological Survey, Urbana, 111. 
3 Research assistant, Illinois State Geological Survey, Urbana, 111. 
^Mechanical engineer, Illinois State Geological Survey, Urbana, 111. 



19 



TABLE 1. - Zinc and cadmium in grab samples of coarse-grained refuse (gob) 



Coal 



Sample type 



Zinc, 
pet 



Cad- 
mium ,, 
pet 



Coal 



Sample type 



Zinc, 
pet 



Cad- 
mium, 
pet 



5 

6 

6 
5 and 6 
5 and 6 
5 and 6 



Gob pile 

■ •••••• CIO •••••••• 

••••••• uu •••••■•■ 

do 

Preparation plant 
do 



0.330 
.006 
.090 
.520 
.440 
.640 



0.0031 
.0001 
.0007 
.0006 
.0002 
.0007 



5 and 6 
5 and 6 

5 

5 

5 

5 



Preparation plant 
.do . . 
.do. . 
• do . . 
.do . . 
.do . . 



0.230 
.050 
.220 
.150 
.100 
.010 



0.0021 
.0004 
.0032 
.0018 
.0011 
.0002 



TABLE 2 . - Zinc and cadmium in grab samples of fine-grained 

refuse deposits (slurry wastes) 



Coals 


Zinc, pet 


Cadmium, pet 


Coals 


Zinc, pet 


Cadmium, pet 


6 


0.130 


0.0015 


5 


0.010 


0.0001 


6 


.270 


.0025 


2 


1.750 


.0190 


5 


.650 


.0071 


2 


2.360 


.0280 


5 


.320 


.0038 


2 


.110 


.0013 


5 


.410 


.0048 









TABLE 3. - Zinc and cadmium in washed coal samples 



Coal 


Sample description 


Zinc, pet 


Cadmium, pet 


5 and 6 


Coal (minus 6 plus 3 in) .... 


0.010 


0.0001 


5 and 6 


Coal (minus 3 plus 1-1/4 in) 


.020 


.0001 


5 and 6 


Coal (minus 1-1/4 plus 
3/4 in). 


.007 


.0001 


5 


Coal (1-1/2 in) 


.025 


.0005 



The Humphreys spiral concentrator produced first-stage coal and heavy 
mineral concentrates from the refuse fan. There was a 324-pct average effec- 
tive increase in the zinc content of the heavy mineral concentrate. The total 
carbon content in the coal concentrate increased an average of 72 pet. The 
best coal concentrate contained 97 pet coal and only 3 pet discrete mineral 
particles. Chemical analyses showed this coal concentrate to contain 2.6 pet 
total sulfur and 9 pet ash. Secondary and tertiary beneficiation stages could 
be expected to further improve the quality of these concentrates. 

References 

1. Hatch, J. R., H. J. Gluskoter, and P. C. Lindahl . Sphalerite in Coals 

From the Illinois Basin. Econ. Geol . , v. 71, No. 3, 1976, pp. 613-624. 

2. Haynes, R. J., and W. D. Klimstra. Illinois Lands Surface Mines for Coal. 

Cooperative Wildlife Research Laboratory, Southern Illinois University, 
Carbondale, 111., 1975, 201 pp. 

3. Smith, W. H., and D. J. Berggren. Strippable Coal Reserves of Illinois, 

Part 5A — Fulton, Henry, Knox, Peoria, Stark, Tazewell, and Parts of 
Bureau, Marshall, Mercer, and Warren Counties. 111. Geol. Survey 
Circ. 348, 1963, 59 pp. 



20 



UTILIZING BAYER PROCESS MUDS: PROBLEMS AND POSSIBILITIES 

by 
B. K. Parekh 1 and W. M. Goldberger 2 



Aluminum metal and aluminum oxide products are made almost entirely from 
bauxite, a naturally occurring mixture of hydrated aluminum oxide minerals. 
Silica, iron oxide, and titania are generally present in various amounts, and 
other elements occur in trace elements. Typical analyses of different baux- 
ites are given in table 1 . 

TABLE 1. - Typical analyses of various bauxites 1 



Constituents 



A1 2 
Si0 2 
Fe 2 
TiOo 



3, total, 
3 



p 2 o 5 
v 2 o 5 

H 2 0, 
A1 2 
A1 2 



combined , 

3 , trihydrate. , 
o, mono hydrate, 



Jamaican Surinam Arkansas Guyana 



49.2 

.7 

19.3 

2.5 

NA 

.4 

.03 

26.5 

44.4 

2.8 



Weight-percent 



55.0 
3.8 
7.0 
2.4 
NA 
.06 
.04 
31.2 
50.0 
.2 



48.7 

15.3 

6.5 

2.1 

.2 

NA 

NA 

25.8 

34.1 

14.6 



58.6 
4.9 
4.1 
2.5 

.02 

NA 

NA 

29.6 

52.7 

5.9 



NA Not available. 

Analyses provided by the operating company. 

Alumina (A1 2 3 ) is extracted from bauxite by the Bayer process. For 
bauxite containing high amounts of reactive silica, a combination process is 
used that incorporates a lime sinter step with the Bayer process. The major 
process waste producing alumina is the leach residue from the caustic diges- 
tion of bauxite. This waste material can be claylike in nature and is gener- 
ally referred to as "red mud" because the iron oxide content usually imparts 
a red color to the waste. Residues from processing the bauxite by the combi- 
nation process are called "brown muds . " 

This waste mud is pumped from the processing plants as a slurry contain- 
ing about 20 pet solids and is impounded in mud lakes. Approximately 10 mil- 
lion tons of mud waste are generated annually in the United States (table 2) . 



■"•Research scientist, Battelle Columbus Laboratories, Columbus, Ohio. 
2 Senior research leader, Battelle Columbus Laboratories, Columbus, Ohio. 



21 



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From the standpoint of effluent control, impoundment is not an ideal sol- 
ution to the mud waste disposal problem. Mud lakes require a significant 
amount of land because the settling rate of solids is generally very slow. 
The land area committed to impoundment at each plant site is about 2,000 to 
3,000 acres. The dikes of a mud lake must be maintained, and there is always 
risk of a break and spill of the mud into a nearby stream or waterway. Cer- 
tain muds are almost thixotropic in character, and even the old, apparently 
dried mud lakes cannot support heavy equipment or construction. The problems, 
of course, vary with the source of bauxite and the location of the process 
plants . 

The use of the muds for recovery of metals has emphasized the extraction 
of iron. Recovery of titania and additional alumina has been of some interest 
also. Some attention has been given to the technology of extraction of the 
higher unit value metals niobium, gallium, and vanadium. However, commercial 
recovery has not been tried because of the very low concentration of these 
elements . 

Several processes have been developed to recover iron from the red mud 
residues. One method is the carbon-lime-soda sinter processes which can be 
applied to ore or to the red mud (1, 3) . In this process, the iron is reduced 
and recovered by magnetic separation from the waste residues after the alumina 
has been leached. 

Direct electric arc smelting of the red mud has been proposed for recovery 
of iron from high-iron-content bauxites (5) . In this case, pig iron can be 
produced with up to 98 pet recovery of the iron content of the bauxite. The 
slag from the smelting can also be further treated to recover up to 84 pet of 
the alumina lost by the Bayer process . This particular process was advocated 
as being both technically and economically feasible based on pilot-plant-scale 
development work. The economics assume that the pig iron or steel would be 
produced near the bauxite-refining plant to take advantage of low-cost iron 
units. The U.S. iron and steel industry has not taken steps to commercialize 
the process. Economics require a low-cost means to completely dewater the 
mud. Moreover, trace elements present in the muds, for example, phosphorus, 
are recognized to have a very significant and adverse effect on steel quality. 
Numerous other processes for iron recovery are described in the literature (7) . 

Alumina and titania can be recovered from the mud. If the mud is smelted 
for iron recovery, the slag from the smelting operation can be leached with 
sodium carbonate solution to recover most of the alumina. Titania can be 
recovered from the residue by leaching. The extraction of titanium from the 
red mud is technically feasible, but the complicated processing makes this too 
costly to compete with recovery from natural titanium ores such as ilmenite or 
rutile. 

Other rare metals such as gallium, vanadium, and scandium can be recov- 
ered from the red mud residues or at various stages in the Bayer process. 
Gallium recovery from the caustic aluminate liquors (6) is economical. Sev- 
eral studies have also been conducted on vanadium recovery. In one method, a 
vanadium slag is separated in the production of pig iron (2) . In another 



23 



method, liquid-liquid extraction by amines is used on the leach liquors from 
the Bayer process to recover vanadium (4_) . 

The scope of interest in the application of the Bayer muds for ceramic 
products is indicated in table 3. Cement, building blocks, or brick and to a 
lesser extent lightweight aggregate are patented large-tonnage applications 
that could help alleviate the disposal problem. Treatment would be required 
in all cases. Generally some dewatering would be necessary to make red mud 
brick and lightweight aggregate. Acid washing would be required for use of 
the mud as a cement or rubber filler. Complete drying and powder preparation 
would be needed for other filler applications . 

TABLE 3 . - Possible ceramic uses for red muds reported 

in the technical literature 



Field of application 



Number of 
publications 



Cement material , 

Construction block material , 

Lightweight aggregate material , 

Plastic and resin filler , 

Pigment 

Miscellaneous materials recovery , 

Caustic recovery , 

Catalyst material , 

Fertilizer material , 

Coating material , 

Insecticide material , 

Refractory cement material 

Road, pavement, soil stabilization material, 

Metal surface treatment material , 

Sewage treatment material 

Glass material , 

Insulation material 

Coke additive 

Total 



22 
16 
10 
9 
6 
6 
5 
4 
4 
3 
2 
2 
2 
1 
1 
1 
1 
1 



96 



Despite this extensive work worldwide to develop means to utilize Bayer 
process muds, the technology is not available that would allow economic 
processing of muds into products having sufficient existing markets to 
reduce the present need for impoundment. 



24 



References 

1. Calhoun, W. A., and T. E. Hill, Jr. Metallurgical Testing of Hawaiian 

Ferruginous Bauxites, Concluding Report. BuMines RI 6944, 1967, 37 pp. 

2. Fredrich, V. Production of Vanadium Slag From Bauxite Red Mud. Tech. 

Dig., v. 9, No. 7, 1967, pp. 443-444. 

3. Fursman, 0. C, J. E. Mauser, M. 0. Butler, and W. A. Stickney. Utiliza- 

tion of Red Mud From Alumina Production. BuMines RI 7454, 1970, 32 pp. 

4. Gerisch, S., H. Martens, and S. Ziegenbalg. Winning of Vanadium From 

By-Product of Bauxite Treatment. Neue Huette., v. 14, No. 4, April 1969, 
pp. 204-210. 

5. Guccione, E. Red Mud. A Solid Waste Can Now Be Converted to High-Quality 

Steel. Eng. and Min. J., v. 172, No. 9, September 1971, pp. 136-138. 

6. Papp, E. Possibilities of Recovery of Rare Elements From Bauxites During 

Alumina Production by the Bayer Process. Freiberger Forschungsh, 
v. B67, 1962, pp. 117-130. 

7. Parekh, B. K., and W. M. Goldberger. An Assessment of Technology for 

Possible Utilization of Bayer Process Muds. Environmental Protection 
Technology Series, EPA-600/2-76-30, December 1976, 143 pp. 



25 



CONSTRUCTION INDUSTRY EFFORTS TO UTILIZE 
MINING AND METALLURGICAL WASTES 

by 

R. J. Collins 1 



Mining and metallurgical wastes represent one of the largest sources of 
solid waste produced in our society. Each year nearly 2 billion tons of solid 
wastes are generated by the mining and mineral processing industries. Many of 
these materials, because they are essentially rocklike or earthen, have poten- 
tial for use in various forms of construction. Although certain of these 
wastes have been used at one time or another for construction purposes, they 
are generally avoided in favor of conventional materials. Consequently, over 
the years hugh stockpiles of mining and metallurgical wastes have accumulated 
in many areas . 

Because of their similarity to acceptable construction materials and the 
large quantities that are involved, mining and metallurgical wastes should be 
seriously considered as alternative construction material sources in areas of 
the United States where conditions warrant such use. To assess the potential 
of mining and metallurgical wastes for use in some form of construction, it is 
necessary to be aware of the types, locations, available quantities, and gen- 
eral nature of these materials . 

The Federal Highway Administration sponsored a recently completed research 
study aimed at determining the availability of mining wastes and their physical 
and chemical characteristics. Besides developing this much-needed information, 
the study determined the extent to which these waste materials have been uti- 
lized in highway and other types of construction work (1) . Much of the infor- 
mation reported herein was obtained as a result of this study. 

Some understanding of the nature of mining and mineral processing wastes 
is needed prior to discussing the technical, environmental, and economic 
aspects of their use. It is, therefore, essential to classify and describe 
the various types of waste materials resulting from the mining, milling, and 
refining of minerals and ores. These wastes are classified in the following 
general categories: 

1. Waste rock 

2. Mill tailings 

3. Coal refuse 

4 . Metallurgical slags 

The estimated quantities of waste rock, mill tailings, coal refuse, and 
slags produced annually by the mining and mineral processing industries in the 
United States are shown in table 1. Also noted in this table are the esti- 
mated quantities of mineral processing wastes that have accumulated from past 
years of mining activity. 



1 Executive vice president, Valley Forge Laboratories, Inc., Devon, Pa. 



26 



TABLE 1. 



- Inventory of mining and metallurgical waste production and accumulation 

(Million tons per year) 



Mining industry 



Metals: 
Alumina , 
Copper. , 



Gold, 



Iron ore, 



Lead. 



Nickel . . 
Silver. . 
Taconite 
Uranium. , 



Zinc, 



Nonmetals : 
Asbestos 



Barite. . , 
Feldspar , 



Fluorspar , 
Gypsum. . . , 



Phosphate. 



Coal refuse: 
Anthracite 
Bituminous , 



Waste 
rock 1 



Iron and steel slag 
Blast furnace...., 



Steel furnace, 
Total , 



9.2 
688.0 



16.0 



30.0 



.2 
110.0 
172.0 

1.0 



.7 

2.1 
.2 

.1 
15.7 

254.0 



Mill 

tail- 

ings 



2 6.1 
260.0 

6.0 
30.0 

9.0 



.7 

120.0 

6.5 



1,299.8 



7.9 



2.0 

3.4 
.9 

.4 
.3 

3 60.0 



5 .8 
5 100.0 



614.0 



Smelter 
slag 



4.0 



.5 



.4 



4.0 



30.0 



12.0 



Estimated 
total waste 
accumulation 



51.7 



50.0 
,500.0 



500.0 



800.0 



200.0 

15.0 
Uncertain 
4,000.0 
125.0 

200.0 



15.0 

25.0 
Uncertain 

Uncertain 
Uncertain 

^1, 000.0 



1,000.0 
2,500.0 



Uncertain 



Uncertain 



Principal areas of occurrence 



Texas, Louisiana, Arkansas. 
Arizona, Utah, Montana, 

Michigan, Tennessee, 

New Mexico , Nevada . 
California, South Dakota, 

Nevada . 
Minnesota, Michigan, 

Missouri, California, 

Pennsylvania . 
Missouri, Colorado, Kansas, 

Oklahoma . 
Southwestern Oregon. 
Colorado, Idaho, Nevada. 
Northeastern Minnesota. 
Wyoming, Utah, Colorado, 

New Mexico . 
Colorado, Idaho, 

Pennsylvania, Tennessee. 



" 






California, Vermont, Arizona, 

North Carolina. 
Nevada, Missouri, Arkansas. 
North Carolina, California, 

Connecticut . 
Illinois, Colorado. 
Michigan, Texas, Iowa, 

California , Oklahoma . 
Central Florida, Idaho, 

Tennessee. 

Northeastern Pennsylvania. 

Kentucky, West Virginia, 
Pennsylvania, Illinois, Ohio, 
Virginia, Indiana, Alabama. 



Pennsylvania, Ohio, Illinois, 
Indiana, Michigan, Alabama, 
Maryland, California. 
Do. 



^Includes waste rock and overburden in some operations. 
Includes estimated 6 million tons of alumina mud. 
Includes both phosphate slimes and phosphogypsum. 
Includes estimated 150 million tons of phosphogypsum. 
Includes coarse and fine preparation plant refuse. 
NOTE. — The above totals do not include an estimated 75 million tons of 
(including dusts) which are generated annually by crushed stone, 
and slate quarries and by sand and gravel pit operations. 



- 



solid wastes 
building stone, 



27 



One means of assessing the suitability of waste rock in construction is 
to determine the extent of use and performance record of various waste rock 
sources for this purpose. It is also important to remember that many waste 
rock materials have been successfully used by mining companies for years in 
the construction of embankments and haul roads on mining property. 

The huge quantities of mining and metallurgical wastes that have been 
accumulated are currently being produced in many areas throughout the United 
States. Many of these materials have been successfully used in some form of 
highway construction or are potentially suitable for this purpose. Certain 
materials, such as iron ore waste rock, coarse taconite tailings, phosphate 
slag, and properly aged steel slag, possess unique properties and are actually 
superior to most conventional construction materials. Other sources of 
mineral wastes, such as coarse tailings and coal refuse, are quite acceptable 
for some construction uses, provided they are properly prepared and applied. 

A greater awareness and recognition is needed of the existence and use- 
fulness of many of these byproducts . Sizable quantities of these materials 
are often available near areas where the supply of conventional aggregates is 
diminishing. A large number of mining and metallurgical wastes are well 
suited to construction use. Their utilization would in many cases improve 
the quality of facilities in which they were applied, reduce costs, and con- 
serve badly needed natural resources. In addition, the potential for savings 
in energy by substitution of certain byproducts is an important consideration 
which further recommends their utilization. 

Reference 

1. Collins, R. J., and R. H. Miller. Availability of Mining Wastes and Their 
Potential for Use as Highway Material. U.S. Department of Transporta- 
tion, Federal Highway Administration, Rept. FHWA-RD-76-106, May 1976, 
294 pp. 



28 



IRON RECOVERY AND GLASS FIBER PRODUCTION FROM COPPER SLAG 

by 
C. H. Chung, 1 T. Mizuno, 1 and J. D. Mackenzie 2 



The present total capacity in the United States for processing copper 
from porphyry copper ores is estimated to be 1,592,000 tons of ores annu- 
ally ( 5) . The maximum amount of slag produced, assuming full production, is 
849,000 tons per year (1}. This presents a serious environmental problem. 
On the other hand, this slag could be considered as a raw material for ceramic 
products. Most of the efforts to solve this problem were based on the con- 
version of the copper slag into glass ceramic (2-4) . However, precipitation 
of magnetite (Fe^), maghemite (y-Fe 2 3 ), and hendenbergite (CaO»FeO«2Si0 2 ) 
occurred during heat treatment of the glass, and controllable crystallization 
was difficult (_3_) . The research was directed to converting the slag into 
glass fiber and also to recovering the iron via a feasible process. 

The total iron content in the copper slag corresponds to the equivalent 
of ~47 pet Fe203« Most of this iron exists in the form of fine maghemite 
particles embedded in the slag. The extraction of this iron oxide by conven- 
tional mechanical and magnetic separation processes is difficult. The manu- 
facture of glass from the copper slag also requires a melting temperature in 
excess of 1,500° C because of the low alkali and alkaline earth contents. The 
energy necessary in melting is therefore considerable. The high iron content 
in the slag also created problems in the corrosion of refractories. A typical 
analysis of a copper slag is shown in table 1; the Fe 2 3 content is 47.1 pet. 

The chemical compositions of the glass and the iron produced from copper 
slag are shown in tables 1 and 2, respectively. The iron metal was found to 
contain 1.6 pet Mo and 0.78 pet Cu. Presumably because the iron was formed at 
a temperature below 1,535° C, the samples were fairly porous. The bulk 
density was 6.88 grams per cubic centimeter, compared with the theoretical 
density for pure iron of 7.86 grams per cubic centimeter. 

The glass was dark brown in color because of the high content of iron 
oxide. Some physical and chemical properties measured are shown in table 3 
in comparison with those of common window glass. The fibers were light brown 
in color. Continuous fibers were readily made and showed no surface 
crystallization. 



Research assistant, Materials Department, School of Engineering and Applied 
Science, University of California at Los Angeles, Los Angeles, Calif. 

Professor, Materials Department, School of Engineering and Applied Science, 
University of California at Los Angeles, Los Angeles, Calif. 



29 



TABLE 1. - Composition of copper slag and glass, wt-pct 



Si0 2 . 
AI2O3 
Fe203 
CaO.. 
MgO.. 
Ti0 2 . 
CuO.. 
ZnO.. 



Compound 



Copper s 


lag 


Glass 


34.3 




49.0 


5.2 




14.0 


47.1 




17.0 


9.1 




14.0 


1.5 




1.5 


.5 




.8 


.3 




.1 


.7 




.6 



TABLE 2. - Composition of metal from copper slag, 

wt-pct 



Fe. 
Mo. 
Cu. 

Co. 

Sn, 
Si, 
Ni, 
C. , 



97.5 
1.6 
.78 
.057 
.016 
.013 
.007 
.012 



TABLE 3. - Properties of glass from copper slag 
compared with window glass 



Glass transition temperature C . . 

Thermal expansion coef f iciency 

Alkali resistance mg/cm . . 

Hardness (Knoop) kg/mm . . 

Density g/ cm • • 



Copper slag 
glass 



623 

61 X 10 -7 

0.22 

823 

3.41 



Window glass 



530 



90 X 10 



-7 



0.25 

443 

2.50 



Based on the present preliminary work, it appears that the continuous 
production of iron and glass fibers from copper slag is feasible. A sche- 
matic drawing of a possible continuous melting tank is shown in figure 1. 
Dense zircon refractory can be used for the inside wall of the tank. A_ 
movable dense zircon plug in section A allows the metallic iron to be with- 
drawn from the melt periodically. The batch can be charged from the top of 
zone A. Zone B is the homogenization furnace where the temperature can be 
kept at 1,350° C or higher. Zone C should be maintained at 950 C if fiber 
is made by the updraw method, or somewhat higher if glass wool is made by 
downdraw. 



30 




1. 



4. 
5. 



•Burners' Zone 

D Fire Brick. 

@ Burned Impregnated Dolomite 

2) Synthetic Mulite. 

Dense Zircon. 



FIGURE 1. - Proposed tank design for continuous production of iron and glass fibers 
from copper slag. 

References 

Biswas, A. K. and W. C. Davenport. Extractive Metallurgy of Copper. 
Pergamon Press, New York, 1976, 438 pp. 

Pavlushkin, N. M., T. D. Nurbekov, and L. S. Egorova. L. S. Izv. Akad. 
Navk. SSSR. Neorg. Mater, v. 4, No. 8, 1968, pp. 1390-1391. 

Stavrakeva, D., and V. V. Lapin. Stulio Fina Keram. Nauchno-Tekh . Konf. 
3th, 1970, pp. 173-181. 

• Stroit. Mater. Silikat prom., v. 14, No. 2, 1973, pp. 11-14. 



Sutulov, A. Copper Porphyries. The University of Utah Printing Services 
Salt Lake City, Utah, 1974, p. 188. 



31 



MUNICIPAL REFUSE 

RESOURCE RECOVERY FOR MUNICIPAL SOLID WASTE DISPOSAL—AN OVERVIEW 

by 
P. J. Cambourelis 1 



Archeo logical information on the nature of man's earliest societies comes 
primarily from examination of discarded materials left on what was then open 
countryside. In a nomadic society, populating the surface of the earth very 
sparsely, there was no reason for concern. Even as man "settled down" and his 
numbers increased, the problem of waste disposal continued to be insignificant. 
Man, of necessity, lived a frugal existence, repairing and reusing articles as 
often as possible. What little waste materialized, because population densi- 
ties were still quite low, was moved out of man's way with little inconvenience, 

The industrial reveoltion changed all this. Society began large-scale 
use of materials for increasing quantities of mass-produced goods. The system 
required population to be concentrated around the centers of production. The 
overall population trend in the United States, together with the trend in 
urbanization, is shown in figure 1. The more affluent segments of society, 
including developed nations such as the United States, used manufactured goods 
for shorter and shorter periods. The consumer society recognized and accepted 
concepts of planned obsolescence and nonreusable goods and containers. 

Energy consumption followed suit . For a while it was cheaper to leave 
electric lights on continuously in large office buildings than to turn them 
off during off hours. In the United States mass transportation gave way to 
automobiles within two generations. Commuting to work by auto became normal. 
In the very recent past, commuting usually involved only one passenger-driver 
per 3,500-pound vehicle. 

The trend in energy consumption began to change in the 1960's when we 
began to see strange-looking but relatively light, low- fuel-using Volkswagen 
Beetles on our highways. The 1960 's also spawned a reexamination of some of 
the effects of the consumer society on quality of life and on what had become 
a rapidly degrading environment. The U.S. Environmental Protection Agency 
(EPA) emerged during this time, originally as an arm of the Housing and Urban 
Development Agency (HUD) and finally on its own as a Federal agency reporting 
to the President. 

Both air and ground pollution were recognized as serious problems. Even 
the oceans, covering 70 pet of the Earth's surface, were affected. For exam- 
ple, surprisingly high heavy-metal contamination was found in certain fish, 
and dangerous trace quantities of residual, chlorinated hydrocarbons were 
detected in birds. Political-legislative action followed the increasing 

iManager, Business Development, Raytheon Service Co., Burlington, Mass. 



32 




</» 

c 
o 

i 

a! 

_i 

CL 

o 

UJ 



social awareness of serious 
environmental problems 
developing. 

The U.S. Bureau of 
Mines pioneered with two 
pilot plants extracting 
fuel, metals, and glass 
from municipal waste. 

EPA was established and 
initiated large-scale 
resource recovery demonstra- 
tion programs; it now devel- 
ops and monitors environ- 
mental quality standards. 

The Clean Air Act had a 
very drastic effect on incin- 
eration of wastes and open 
burning dumps. Required 
additions of sophisticated, 
electrostatic precipitation 
equipment to refractory- 
lined incinerators often 
cost significantly more than 
the incinerators themselves 
had cost originally. Water 
quality and pollution con- 
trol legislation resulted in 
the emergence of proposed 
guidelines for control of 
landfill practices. Efflu- 
ent discharge limits and 
harmful leachate controls 
needed to protect water sup- 
There is little doubt that the Resourrp r™ . PlieS ^ n ° W emer 8 in 8- 
will result, eventually, inltrlt?^ £T ^i^s . *™* A " ° f »* 

net ^otll^T^lTZtll PoliScaf^t is **««** P**-** °n 
atlons also significantly'affect selection 'p^k'',^ geographic consider- 
have critical impact on schedule ft™™? P °i" lcal considerations usually 
P on schedule, financing, and contractual requirements. 

danced T=^t7=^^Z a^aht^ consign .^ 

Financing and contractual options alQn nw«rij 
tives for consideration. Since detail^ H? V 1 * 6 range ° f alter ^- 
beyond the scope of this paper tW d± * cua *">* of these considerations is 
f or cnxs paper, they are only mentioned briefly. 



1910 1930 1950 1970 



1790 1810 1830 1850 1870 1890 

YEARS 
FIGURE 1. - Urban and rural population. (1976 U.S. 
Bureau of Census Statistical Abstract.) 



33 



TABLE 1 . - Current resource recovery projects 1 



Major system category by type 
of energy recovery 



Number 

of 
plants 



Total 

capacity, 

tons 

per day 



Total 
capital, 
million 
dollars 



Average 
capital 

cost, 
thousand 
dollars 
per ton 
of daily 
capacity 



Direct combustion 

Refuse-derived fuel for dedicated boiler 

Refuse-derived fuel for sale 

Pyrolysis 

Pulverized refuse-derived fuel 

Hydropulping 

Bioprocessing 

Total 



1,560 
3,500 
8,450 
1,400 
4,000 
5,150 
100 



76.5 

121.0 

138.0 

59.5 

90.0 

158.2 

3.1 



49,000 
34,600 
16,300 
42,500 
22,500 
30,700 
31,000 



22 



24,160 



646.3 



$26,800 



Percent of 

market 
(capacity) 



All 



Direct combustion 

Refuse-derived fuel for dedicated boiler 

Refuse-derived fuel for sale 

Pyrolysis 

Pulverized refuse-derived fuels 

Hydropulping 

Bioprocessing 

Total 



6.5 

14.5 
35.0 

5.8 
16.5 
21.3 

0.4 



100.0 



Solid 

fuel 

mfM 



87.3 



Dry 
process 
only 



Range of capital 

cost, 

thousand dollars 

per ton of 

daily capacity 



Minimum 



41.6 
30.0 
4.2 
30.0 
10.0 
21.3 
31.0 



66 



4.2 



Maximum 



73.6 
46.0 
25.2 
75.0 
29.4 
38.2 
31.0 



75.0 



• Indicates column head applies for listed item. 

1 Included are operational systems and systems now in construction or final 
design and fully committed. 

Source: National Center for Resource Recovery, October 1977. 

Funding sources include national and State grants, as well as State, 
county, or municipal general obligation bonds. However, revenue bond 
financing appears to have emerged as the dominant approach even though it 
may lead to higher disposal charges . 

Conventional contractual arrangements — that is, use of architectural and 
engineering consultants for design and to prepare bid packages as required for 
competitive bidding for hardware and construction — can be expected for 
selected situations. However, the trend to revenue bond financing appears 
to have reinforced an existing need for overall system management with 
responsibility extending into shakedown and long-term operational phases 
as well. Contractual forms are tending to take on many of the characteristics 
of turnkey arrangements. Full-service contracts are being considered in a 
number of situations. 



34 



| 7.5. 




FIGURE 2. - Supply and demand curves. 



1.5- 



Z 

O 1.0- 



0.5- 



70 


- 






60 






(O&M 


> 








< 








Q 




(3)1 / 




£ 50 


.•*•, 






a. 








z 
o 

I— 


- ■ fl 






5 40 








•SI 








a 








Z 








< 








3 30 








o 








X 








t— 








£ 








^ 20 








Q- 








< 








o 




A / \ 




10 


/— D--/ 


\ / \ 






# ^r 


■ — r N *-^i i 


i 1 



1980 



2000 



FIGURE 3. - Annualized expenditures for 
capital and operating cost. 



The institutional and political complexities referred to above signifi- 
cantly affect the financing and contractural methods used and are believed by 
many to cause much of the 5- and 10-year project delay shown graphically in 
figures 2 and 3. 

In figure 2 the maximum processing capacity potential represented by 
Standard Metropolitan Statistical Areas (SMSA's) of 100,000 people or larger 
is shown. The dollar scale on the left side is based on the $26,800 average 
cost per ton of daily capacity indicated above. Curve 2 is based on a survey 
conducted by Raytheon Service Co. in 1975-76 in which over 150 out of 157 
SMSA s of 250,000 people or more were contacted. At that time over half of 
those contacted indicated plans to initiate resource recovery systems. Curves 
3A and 3B outline a zone within which the path of resource recovery capacity 
is likely to move. Curve 3 shows the early, slow development of capacity that 
has occurred to the present. The dot on curve 3 represents the 24,000 tons of 
capacity represented by current projects. Figure 3 annualizes the cumulative 
data shown m figure 2. Also shown are the projected annual operating and 
maintenance costs that would result as the system developed in accordance 
with the frequency shown on curve 3 becomes operational. Of particular inter- 
est is the observation that sustained annual O&M expenditure levels of about 
the same order of magnitude as expected for peak annual expenditures for 
system acquisition can be anticipated. 

It will be interesting to observe development of the resource recovery 
system business over the next 5 to 10 years, as operating experience accumu- 
lates for the several system types referred to above, under varying funding 
and contractual arrangements. 8 



35 



ALBANY-NEW YORK SOLID WASTE ENERGY RECOVERY SYSTEM (ANSWERS) 
CITY-STATE PARTNERSHIP IN SOLID WASTE ENERGY RECOVERY 
RETURNS PROFIT TO BOTH 

by 

P. F. Mahoney 1 



In October 1976, the City of Albany and the State of New York signed a unique 
20-year agreement which will solve the problems of solid waste disposal for the 
city, and stabilize the rising costs of energy for the State office building complex. 
Under the agreement, the city will process municipal solid waste to produce a fuel 
to be purchased by the New York State Office of General Services (OGS), and OGS 
will construct two new refuse-fired boilers to generate steam to heat and cool the 
Empire State Plaza and other major State buildings located in downtown Albany. The 
refuse-derived fuel (RDF) product will be sold to the State at a 20-pct cost savings 
over the market price for No. 6 fuel oil, the current fuel being used. The contract 
represents an exceptional declaration of cooperation between municipal and State 
governments on a project that will result in significant savings for all parties. 

When the City of Albany first considered the concept of recovering energy and 
materials from solid waste as an alternative to landfilling, the following design 
objectives were established: 

1. To provide an environmentally acceptable, economical alternative to 
landfilling. 

2. To economically produce a competitively marketable fuel or energy product. 

3. To economically recover all recyclable materials for which there is a 
market . 

4 . To design a system which had no environmentally undesirable waste or 
byproducts. 

5. To use only existing or proven technology in the system. 

The system, the Albany-New York Solid Waste Energy Recovery System (ANSWERS), 
is a regional resource recovery program designed to initially process 750 tons per 
day of municipal solid waste, producing a fuel for steam generation and recovering 
all recyclable materials. It developed out of an imperative need to find an alter- 
native to sanitary landfilling in the City of Albany. A municipal commitment to 
preserve the quality of the physical environment and conserve energy together with 
a fuel customer willing to use a processed refuse fuel to save energy and reduce 
costs have been the key ingredients in the development of this project. The amount 
of fuel needed by the State is approximately equivalent to the amount of RDF the 
city can process on a day-to-day basis. Most sifnif icantly, ANSWERS has been 
designed to be a profitmaking venture,, and is, therefore, an economically attractive 
program for all those concerned. 

The project is well under construction, commitments for delivery and purchase 
of fuel have been signed, bid prices have been within the budget, and startup is 
scheduled for May 1980. 

lManaging partner, Smith and Mahoney, Consulting Engineers, Albany, N.Y. 



36 



DIRECT INCINERATION OF MUNICIPAL SOLID WASTE VERSUS 
SEPARATION OF COMBUSTIBLES 

by 

S. L. Law, 1 B. W. Haynes, 2 and W. J. Campbell 3 



This study was conducted as part of the U.S. Department of the Interior, 
Bureau of Mines program to develop technology for increasing the Nation's 
mineral supply through recovery of valuable constituents from currently dis- 
carded waste materials . Municipal solid waste (MSW) , although presently a 
major disposal problem, represents a significant potential source of metals, 
glass, and combustible materials. The technical and economic feasibility of 
physically separating MSW for metal, glass, and combustible fraction recovery 
has been successfully demonstrated in the Bureau of Mines 5-ton-per-hour urban 
refuse pilot plant C5-7) . 

The combustible fraction is approximately 70 wt-pct of the MSW and is 
composed of paper, plastics, yard wastes, putrescibles, wood fabric (table 1), 
and other minor components that are separated from the metals, glass, and 
other noncombustibles during the operation of the pilot plant. This fraction 
can be a valuable supplement to coal in the generation of heat and electricity. 
Evaluation of the combustible fraction as a fuel supplement is an essential 
part of the research leading to total resource recovery from MSW. Although 
the combustibles are a valuable source of energy, as demonstrated by a Bureau 
of Mines evaluation described in BuMines Report of Investigations 8044, some 
resistance to the application of MSW as a fuel supplement has occurred because 
of speculation concerning trace metal emissions to the atmosphere when the 
combustible fraction of MSW is burned together with coal (9) . However, the 
limited data available on combustion of MSW were derived from municipal incin- 
erators where the MSW was not separated into combustible and noncombustible 
fractions prior to incineration (8, 10) . 

If the total MSW is burned, as in municipal incinerators, the emitted 
metals may come from one or both of the two major components of MSW — the com- 
bustible fraction (paper, cardboard, plastics, fabrics, etc.) and/or the non- 
combustible fraction (ferrous metals, nonferrous metals, glass, ceramics, 
etc.). The purpose of this Bureau of Mines study was to determine if separa- 
tion of the combustibles from the total MSW will result in lower concentra- 
tions in the fuel supplement of elements that are objectionable from environ- 
mental considerations. Available data from municipal incinerator studies and 
from analyses of the combustible fractions of MSW, although not originally 
intended for source identification, are used to identify elements and sources 
(table 2). 



Research chemist. 

Chemist 
Supervisory research chemist. 

All of the authors are with the Avondale Research Center, Bureau of Mines, 
Avondale, Md. 



37 



TABLE 1. - Composition of typical refuse, dry basis 



Product 

Ferrous metal 

Aluminum 

Heavy nonf errous metal , 

Plastics , 

Leather and rubber. 

Fabrics , 

Wood , 

Source: Reference 7. 



Pet 



Product 

Corrugated board , 

Paper , 

Putrescibles , 

Glass , 

Miscellaneous , 

Fine glass, grit, dirt, and 
ceramics , 



Pet 



7.6 
1.1 

.2 
5.0 

.7 
1.8 
2.6 



3.5 

51.7 

4.4 

10.5 

.9 

10.0 



TABLE 2. - Elemental input from combustible MSW and output during 
1 week's operation of a model municipal incinerator 





Quantity, kg 


Fraction remaining, pet 


Element 


Input from 


Input from 


Output in 


Not accounted 


Not accounted 




light 


total com- 


incinerator 


for by light 


for by total 




combustibles 1 


bustible MSW 1 


residues 


combustibles 


combustibles 


Ag 


1 


2 


6 


83 


67 


Al 


4,700 


5,800 


5,500 


3 15 


- 


Ba 


80 


110 


120 


33 


3 8 


Ca 


2,900 


6,300 


3,200 


3 9 


- 


Cd 


2 


6 


8 


75 


3 25 


Co 


1 


2 


6 


83 


67 


Cr 


25 


35 


60 


58 


42 


Cu 


80 


230 


50 


- 


- 


Fe 


880 


1,500 


1,500 


41 


- 


Hg 


.5 


1 


1 


3 50 


- 


K 


410 


840 


720 


43 


- 


Li 


1 


1 


2 


3 50 


3 50 


Mg 


640 


1,000 


1,000 


36 


- 


Mn 


60 


80 


230 


74 


65 


Na 


1,900 


2,900 


1,500 


- 


- 


Ni 


7 


10 


50 


86 


80 


Pb 


130 


210 


620 


79 


66 


Sb 


20 


20 


20 


- 


- 


Sn 


10 


10 


90 


89 


89 


Zn 


370 


500 


1,000 


63 


50 



^ased on 920 metric tons (dry weight) of MSW per week, 53 pet light combusti- 
bles, 70 pet total combustibles, and data in references 1, 2, and 4. 

2 Based on 62 metric tons of fine bottom ash (bulk scrap, cans, bottles, etc., 
excluded), 20 metric tons of fly ash, 3.8 metric tons of atmospheric parti- 
cles, and 133,000 liters of recycled water per week (see reference 3). 

3 Could be accounted for by ranges in the original data (1_, 4) . 

Data on metal concentrations in municipal solid waste and in municipal 
incinerator residues have been examined to distinguish between combustible and 
noncombustible sources of the metals that may appear in the residues from the 
combustion of an MSW-derived fuel. Cadmium, chromium, lead, manganese, silver, 
tin, and zinc apparently come from the noncombustible components of refuse as 



38 






well as from the combustibles. The removal of the noncombustible components 
of municipal solid waste by some recycling operation prior to use of the com- 
bustible components for fuel will reduce the concentrations of these seven 
metals. Also, concentrations of antimony, cobalt, mercury, nickel, and pos- 
sibly other metals may be reduced by separating the combustibles from the non- 
combustibles prior to burning. A further reduction of cadmium, copper, and 
other heavy metals possibly can be realized by not including the heavy com- 
bustibles, especially the heavy-gage plastics, in the MSW fuel supplement. 
The light combustibles from MSW are the refuse-derived fuel source containing 
the lowest concentrations of trace and minor elements. 

References 

1. Haynes, B. W., S. L. Law, and W. J. Campbell. Metals in the Combustible 

Fraction of Municipal Solid Waste. BuMines RI 8244, 1977, 16 pp. 

2. . Concentrations and Sources of Trace Elements in the Combustible 

Fraction of Municipal Solid Waste. Proc. 2d Nat. Conf . and Exhibition 
on Technology for Energy Conservation, Albuquerque, N. Mex., Jan. 23-27, 
1978, 4 pp. 

3. Law, S. L. Metals in Ash Materials Filtered From Municipal Incinerator 

Effluents. Resource Recovery and Conservation, v. 3, 1978, p. 19. 

4. Marr, H. W., S. L. Law, and D. L. Neylan. Trace Elements in the 

Combustible Fraction of Urban Refuse. Internat. Conf. on Environmental 
Sensing and Assessment, IEEE, Inc., 1974, p. 4-3. 

5. Phillips, T. A. An Economic Evaluation of a Process To Separate Raw 

Urban Refuse Into Its Metal, Mineral, and Energy Components. 
BuMines IC 8732, 1977, 25 pp. 

6. Sullivan, P. M., and H. V. Makar. Bureau of Mines Process for Recovering 

Resources From Raw Refuse. Proc. 4th Miner. Waste Utilization Symp., 
cosponsored by the Bureau of Mines and IIT Research Institute, 
Chicago, 111., May 7-8, 1974, pp. 128-141. 

7 * • Quality of Products From Bureau of Mines Resource Recovery 

Systems and Suitability for Recycling. Proc. 5th Miner. Waste 
Utilization Symp . , cosponsored by the Bureau of Mines and IIT Research 
Institute, Chicago, 111., Apr. 13-14, 1976, p. 223. 

8. U.S. Environmental Protection Agency. Corrosion Rates in Municipal 
Incinerators. SW-72-3-3, 1972, 96 pp. 

9 - • Use of Solid Waste as a Fuel by Investor-Owned Electric Utility 

Companies. EPA/530/SW, July 1975, 27 pp. 

10. University of Maryland. Atmospheric Impact of Major Sources and 
Consumers of Energy. Progress Report-75, 1975, pp. 118-135. 



39 



PREPARING DENSIFIED REFUSE-DERIVED FUEL ON A PILOT SCALE 

by 
H. Alter 1 and J. Arnold 2 



Refuse-derived fuel (RDF) generally refers to the product of the mechani- 
cal (or chemical plus mechanical) processing of municipal solid waste (MSW) to 
produce a specification fuel. For example, the product of shredding and air 
classification of MSW is one form of RDF. 

By densified refuse-derived fuel (d-RDF) is meant the product of the 
mechanical compaction of some form of RDF to agglomerated pieces which are 
sufficiently cohesive to sustain storage and handling. The term "densified" 
is used in the generic sense to include all manner and forms of compaction, 
such as extrusion or rolling to produce what are commonly called briquets, 
pellets, cubettes, etc. Generally, d-RDF would be intended as a fuel for 
some type of stoker boiler. 

Probably the first d-RDF was prepared by F. C. Stirrup in 1959. using at 
first wood chips and shavings and then municipal refuse. The process con- 
sisted of shredding, suspension drying to 8 to 10 pet moisture, and extru- 
sion. In 1960, Stirrup reported the preparation and properties of extruded 
briquets from German and British refuse on scales up to 6 tons per hour. The 
process consisted of magnetic separation, shredding (using a Novorotor 
grinder), drying in a suspension dryer, and extrusion through a Glomera high- 
pressure briquetting press. A commercial plant for Salford, England, was 
described but apparently never built (5) . 

Stirrup's d-RDF was in the form of large cyclindrical pieces. No dimen- 
sions are given in the early papers, but a single briquet is described as 
weighing some 2% pounds. 

The next pioneering effort to prepare a specification fuel from MSW in a 
form that could be burned on a grate was by Hollander and Cunningham (2) . They 
describe a 30-ton-per-hour plant consisting of shredder, classifier, screens, 
and cubetter to produce cubettes approximately lH by 1% by 2 inches, formed in 
a modified John Deere alfalfa cuber. Approximately 40 tons of these cubettes 
were burned with coal (2) . 

This early work did not lead directly to full-scale plants; perhaps it 
was just "before its time." Now, however, interest in d-RDF is high, and 
several organizations are investigating and preparing d-RDF on pilot scales. 
One plant is doing so on a commercial scale of 60 metric tons per day (4) . 
In 1976-77, the National Center for Resource Recovery equipped its pilot plant 
to produce d-RDF for investigative purposes; the Center's equipment test and 
evaluation facility has been described (1) . 

iDirector of resource programs. 
Senior research engineer. 

Both authors are with the National Center for Resource Recovery, Inc., 
Washington, D.C. 



40 



A 300-ton operating period provided fuel for test burns at the powerhouse 
of the Men's Correctional Institution, Hagerstown, Md., through the coopera- 
tion of the Department of General Services, State of Maryland. The test burns 
were conducted by Systems Technology Corp. under contract to the U.S. Environ- 
mental Protection Agency, Office of Research and Development, Municipal 
Environmental Research Laboratory. The results of these experiments will 
soon be reported (3) . Additional fuel is being prepared and stored for test 
burns to be conducted in 1978. 

References 

1. Alter, H., S. L. Natof and L. C. Blayden. Pilot Studies Processing MSW 

and Recovery of Aluminum Using an Eddy Current Separator. Proc. 5th 
Miner. Waste Utilization Symp., cosponsored by the Bureau of Mines and 
IIT Research Institute, Chicago, 111., Apr. 13-14, 1976, pp. 161-168. 

2. Hollander, H. I., and N. F. Cunningham. Beneficiated Solid Waste Cubettes 

as Salvage Fuel for Steam Generation. Proc. 1972 National Incinerator 
Conf . American Society of Mechanical Engineers, New York, 1972, 
pp. 75-86. 

3. Rigo, H. G., G. Degler, and B. T. Riley. A Field Test Using Coal: d-RDF 

Blends in Spreader Stoker Fired Boilers. Draft Interim Report. 
Systems Technology Corporation for Municipal Environmental Research 
Laboratory, U.S. Environmental Protection Agency. (To be issued.) 

4. Societe d' Etudes et d'Inginierie. 3 rue Largilliere, 75016 Paris. 

(The plant itself is located in Laval . ) . 

5. Stirrup, F. L. Public Cleansing; Refuse Disposal. Pergamon Press, 

London, 1965, pp. 132-136. 



41 



ALUMINUM SCRAP RECOVERED FROM FULL-SCALE MUNICIPAL 
REFUSE PROCESSING SYSTEMS 

by 

G. F. Bourcier 1 and K. H. Dale 2 



The growth pattern of the aluminum reclamation (formerly secondary) 
industry has followed the growth in production and use of primary aluminum. 
The reclamation industry functions as a supplementary, but very important, 
source of metal for our economy. Aluminum scrap has comprised 15 to 25 pet 
of domestic aluminum ingot supply over the last 35 years and has remained at 
about 22 pet for the last 10 years (1) . Today, from our perspective in the 
aluminum industry, we look at recycling as conceptually capable of providing 
scrap aluminum through two complementary approaches . 

To identify the sources of aluminum scrap and the quantity of scrap 
available from these sources, a study was made by Battelle Columbus Labora- 
tories that would identify the categories of scrap metal on the basis of its 
original market (3). The study, published in 1972, was limited to old scrap 
(that is, metal objects that had been discarded after use). In contrast, new 
scrap is that scrap recovered directly from manufacturers and fabricators. 
In 1969, the total quantity of aluminum scrap processed was 1.15 million tons; 
200,000 tons of this was old scrap but this was only 13 pet of the available 
old scrap. By 1975, 334,000 tons of old scrap was recycled; this was an 
estimated 17 pet of that available. Old scrap usage increased to 416,000 
tons in 1976, the last year for which statistics are available. 

The advent of resource recovery from municipal refuse has added breadth 
to the supply of old scrap potentially available to industry. The growing 
use of aluminum in automobiles indicates that the transportation market, at 
some point in the future, will provide even more substantial amounts of 
aluminum scrap and, concurrently, increase the potential market for aluminum 
scrap (3) . 

Recovery of aluminum from municipal refuse is not as simple as ferrous 
recovery. In today's systems, aluminum is generally recovered from shredded 
or similarly processed refuse after a series of concentrating steps that first 
remove organics, magnetics, and the fine glass and dirt, leaving a concentrate 
enriched in aluminum that can be further processed using any of several 
methods (2) . 

The first and most widely discussed recovery method is the eddy current 
separator, of which there are several types now in use. The basis of the eddy 
current separator is to pass the material to be processed through an electro- 
magnetic field, which for the most part is of a magnitude and frequency that 

1 Manager, resource recovery programs. 
2 Senior development project director. 
Both authors are with Reynolds Metals Co., Richmond, Va. 



42 



are proprietary to the individual equipment manufacturer and peculiar to his 
specifications. The electromagnetic field induces eddy currents in any elec- 
trical conductor present, which is then repelled by that field. 

Another method of aluminum recovery from refuse is the use of dense-media 
separation, which basically is the flotation of aluminum in an aqueous slurry 
of magnetite and ferrosilicon, or other dense minerals such as bariet or 
galena. Nonferrous metals from auto shredders are currently being processed 
by heavy-media separation facilities in about a dozen separate locations. An 
analog of these dense-media systems, for processing nonferrous metal concen- 
trates from municipal refuse, is being seriously considered by Reynolds. 

The characteristics of aluminum scrap recovered from refuse using eddy 
current separators Include contamination with other nonferrous metals or 
organics such as rags, paper, and film plastic. This may be compensated for 
by cleaning up the eddy current separator product with an air knife, screens, 
heavy-media separation, sweat furnace processing, or handpicking. 

The eddy current separators currently in use, although similar in princi- 
ple, can produce differing grades of aluminum scrap. However, an eddy current 
separator subsystem can be set up to recover whole or partially crushed alumi- 
num cans and large aluminum scrap objects, such as frozen food dishes, while 
missing most other aluminum scrap, such as crumpled foil. 

Aluminum scrap recovered from processed municipal refuse using dense- 
media systems will generally be under 2 inches in size and include most of the 
aluminum in refuse, including scrap cans, castings, foil, etc. Analysis of 
this scrap may also show small amounts of zinc, insulated copper wire, or 
glass (which often has the same specific gravity as aluminum) . Losses of 
aluminum to the sink fraction in dense-media processing or to the float frac- 
tion in the water elutriation step (generally performed prior to the dense- 
media operation) could be troublesome if the system is not run properly. In 
contrast, aluminum recovered from nonmagnetic auto shredder residues will 
often have a much larger average particle size (nominally in the 2- to 6-inch 
range) owing to the nature of auto shredders and the physical size of aluminum 
components in autos vis-a-vis the size of aluminum found in refuse. 

Analytical data indicates that current state-of-the-art aluminum recovery 
equipment is capable of recovering a good grade of aluminum scrap. Additional 
unit operations may be necessary to upgrade the aluminum scrap recovered, 
depending on the end use required. There is a ready market for the aluminum 
scrap recovered if it is consistent in assay recovery and chemistry. 

References 

1. Aluminum Association. Aluminum Statistical Review, Washington, D.C., 

1976, p. 27. 

2. Bourcier, G., and K. Dale. Technology and Economics of the Recovery of 

Aluminum From Municipal Solid Wastes. Resource Recovery and Conserva- 
tion, v. 3, 1978, pp. 1-18. 

3. Dale, K. H. Recovery and Recycling of Automotive Aluminum. Proc. Soc. 

Automotive Eng., February 1978, Paper 780251. 



43 



TEST RESULTS AND APPLICATION IN COMMERCIAL MUNICIPAL SOLID WASTE PLANTS 

by 
C. Cederholm 1 



The costs of handling domestic refuse are becoming increasingly heavy, 
while the shortage of raw materials is becoming steadily more acute. Bearing 
in mind that half of domestic refuse consists of paper and that the raw mate- 
rial for paper is in short supply in Sweden, this is something of a paradox. 
Thus, there is every reason to apply modern technology to a more efficient 
use of our raw material resources. 

Several factors have thrown recovery techniques into the limelight. 
According to a large number of forecasts, the shortage of raw materials in 
Sweden is likely to become increasingly acute in several fields. In particular, 
a shortage of 1 million tons of paper fiber is predicted by 1980. A large pro- 
portion of consumed raw material is available in domestic refuse. Furthermore, 
the disposal of domestic refuse is expensive and costs increase as environ- 
mental demands become more stringent. Costs also increase because existing 
methods are labor intensive and involve expensive transport operations. 

To meet future requirements and obtain an economic utilization of 
resources, Sweden passed a law in mid-1975 giving the Government full author- 
ity to demand that each community with the financial means start a first-stage 
sorting operation for newspapers and magazines . A preparatory period of 
5 years has been allowed prior to application of the new law, so that com- 
munities can make necessary preparations and investigations as regards suit- 
able methods . 

To a certain extent, and with varying degrees of success, the idea of 
recovery has long been applied at the source in collection campaigns. Experi- 
ments in carrying this out on a more regular and controlled basis have been 
made in the past and are continuing. However, collection at the source has 
a number of shortcomings. These include the following: 

1. The costs of collection and special treatment are fairly high. 

2. The sorting discipline varies. 

3. Uncontrolled proportions of materials are collected. 

4. Unsatisfactory flexibility in adapting the collection to new and 
varying requirements . 

It is, therefore, very important to study alternative solutions employing 
central treatment plants, in which unsorted refuse can, basically, be fed into 
one end and usable raw materials discharged from the other (fig. 1). 

lGeneral manager, solid waste management, AB Svenska Flaktfabriken, Stockholm, 
Sweden . 



44 



AIR CLASSIFIER 1 




OO SHREDDER 2 



LIGHT 
PAPER 



HEAVY 
*\z==i PAPER 



FIGURE 1. - Flowsheet of RRR pilot plant in 
Stockholm, Sweden. 



During recent years, a 
large number of tests have 
been carried out and pilot 
plants operated all over the 
world. The term "recovery" 
has become a catchword which 
is used and abused to jus- 
tify a wide variety of activ- 
ities . Recovery is a common 
term for a number of techni- 
cal solutions adopted to 
utilize, partially or 
entirely, the latent economic 
value of refuse. Recovery 
can be divided into three 
categories : 

Direct recovery of 
substances . — Material recov- 
ered becomes new products 
similar in nature to the 
original products. 

Indirect recovery of 
substances . — Material recov- 
ered may be used for new 
applications that differ 
entirely from the original 
product. 

Recovery of the energy 
content in refuse . — Material 
recovered is used in combus- 
tion, pyro lysis or biochemi- 
cal decomposition processes, 
which liberate heat or 
produce fuel . 



The value of the material recovered is obviously a very important factor, 
since it affects the revenue from the recovery process. 



Analysis of the annual operating and capital costs of a recovery plant 
is equally important, in order to establish profitability at varying levels 
of revenue from recycled materials . It should be clearly borne in mind that 
the present, relatively expensive methods of disposal need not necessarily be 
turned into profitmaking ventures in the future. As a first stage, it is 
sufficient to reduce the overall handling costs. 



45 



Gross cost of 
treatment 
US Dollars/ 
ton 



5 ■ 



Market price of recovered 
materials (38%) 
US Dollars/ton 




''■MttitMcnitiMftiiaita 

' Capital costs 



,10 



40 



80 



120 



160 



100 



THOUSAND TONS PER YEAR 

FIGURE 2. - Gross cost of treatment in relation to plant 
capacity. 

and ferrous metals) at an efficiency of 38 pet and 
would make the system economically self-supporting 



Figure 2 gives an 
example of the specific 
costs of processing and 
the revenue per ton of 
processed material, after 
allowances for operating 
costs and depreciation- 
(10 years for machines, 
20 years for buildings, 
and a 10-pct rate of 
interest) . It relates to 
a plant with an assumed 
capacity of 100,000 tons 
per year. The operating 
costs, including energy 
(and heat for drying) , 
maintenance, service and 
personnel, amount to 
approximately $5 per ton, 
whereas the annual capital 
costs amount to $8 per 
ton. This means that the 
average revenue from the 
material recovered (paper 
selling at $30 per ton 



Research and development work has led to functional and practical systems 
for the recovery of materials, thus allowing communities to conserve their 
resources and at the same time significantly reduce processing costs. 

The profitability aspect changes radically with respect to raw materials. 
What was earlier regarded as useless suddenly gains in value. Municipal solid 
waste can thus become an important raw material in the production cycle. The 
recovery of materials will also have an important role to play in the national 
economy, owing to the energy gains that can be made in refining recycled 
material as compared with fresh raw material. Moreover, significant environ- 
mental gains can be achieved by reducing pollution of earth, air, and water. 



46 



PROGRESS IN PRODUCING DETINNED STEEL FROM URBAN REFUSE MAGNETIC FRACTIONS 

by 
H. V. Makar 1 and E. L. Gresh 2 



Two processes have been developed by the Bureau of Mines, U.S. Department 
of the Interior, for recovering materials of value contained in urban refuse 
as part of the Bureau's mission to conserve the Nation's mineral resources 
through secondary recovery. One process applies to municipal incinerator 
residues and the other to raw, unburned refuse. Both are operated regularly 
on a pilot scale, and details have been published previously (4, _7, 10-11) . 
Current research is concentrated on raw refuse processing, with a lesser, 
but significant effort on incinerator residues. Intense interest has devel- 
oped in this country and abroad toward implementing "front-end" separation 
technology. Several commercial-scale units are already in operation, and 
others are in various stages of planning or construction (12) . Thus, a 
resource recovery industry for improved management of urban refuse is devel- 
oping rapidly. 

In the meantime, there is much that can be done on a pilot scale to aid 
government and private organizations in planning new plants and in determining 
the recyclability and value of materials reclaimed from refuse. To meet such 
a need, a raw refuse pilot plant in Edmonston, Md., is operated on a regular 
basis to (1) generate products for analysis and suitability for recycling, 
(2) provide technical assistance to government and other organizations to 
enhance technology transfer, and (3) continue evaluation of the existing 
process flowsheet and determine what, if any, modifications should be made 
to accommodate refuse composition variations or to improve product recovery 
and quality. 

Evaluations of products generated in the pilot plant are conducted 
in-house and by potential consumers to establish recyclability and market 
acceptance. Standards for ferrous scrap from urban refuse are currently under 
development in Committee E38 of the American Society for Testing and Materials 
(ASTM) . These include specifications for chemical composition and certain 
physical requirements for scrap destined for five different industries. Pro- 
posed standards under consideration are summarized in table 1. In addition to 
the chemical and physical requirements shown, the proposed specifications 
include limitations regarding form (baled or loose) and processing technique 
(incineration, shredding) . 

Properly prepared scrap could meet most of the proposed specifications 
without detinning, but use would be restricted to relatively small quantities 
to minimize buildup of residual elements. After detinning, however, the scrap 
can be used with few restrictions and command the higher prices typical of the 



Supervisory metallurgist. 
2 Metallurgist . 
Both authors are with Avondale Research Center, Bureau of Mines, Avondale, Md, 



47 



traditional top grades of scrap. In addition, the tin resource contained in 
the scrap is recovered as a separate product. 

TABLE 1 . - Proposed specifications for ferrous scrap from refuse, pet 



Component 



Copper 
precipi- 
tation 



Industry 



Iron and steel 



Foundries Production 



De tinning 



Ferro- 
alloy 



Carbon 

Manganese 

Phosphorus 

Sulfur 

Silicon 

Nickel 

Chromium 

Molybdenum 

Copper 

Tin 

Lead 

Zinc 

Aluminum 

Titanium 

Metallic yield min...pct. 
Combustibles, max.... pet. 
Bulk density lb/ft 3 . 



NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 

( 3 ) 

.2 

30.0 



NAp 

NAp 

0.03 
.04 

NAp 
.12 
.15 
.04 
.20 

2 .30 
.03 
.06 
.15 

NAp 
90.0 

4.0 
50.0 min. 



NAp 
NAp 
0.03 

.04 

.10 

.08 

.10 

.025 

.10 

.30 

.15 

.06 

.15 
NAp 
90.0 
4.0 
75.0 min, 



NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
NAp 
0.15 min, 
NAp 
NAp 
4.0 
NAp 

( 4 ) 

NAp 

25.0 min, 



0.6 
.35 
.03 

NAp 

NAp 

NAp 
.15 

NAp 
.20 
.30 

NAp 

NAp 
.15 
.025 
90.0 
.5 
50.0 min. 



NAp Not applicable. 
Maximum limits, unless 



>therwise designated. 
:ing is 0.10 maximum. 



2 Tin limit for steel cast: 

3 96 pet iron, minimum. 

4 A minimum of 95 pet of scrap shall be magnetic. 



Detailed data on chemical composition are extremely limited for the vari- 
ous commercial grades of steel scrap currently marketed. Table 2 summarizes 
various scattered data that have been published (3, 5_, 8.-9) . Other published 
data for tin content show 0.025 pet average for all purchased scrap and up to 
0.075 pet in iron ore (2). The chromium coating on tin-free steel cans repre- 
sents less than 0.01 pet (1, 6). Even at the higher percentage of 17 pet tin- 
free cans shown in table 3, chromium in the scrap attributable to this source 
would be less than 0.002 pet. 

The Bureau of Mines, in cooperation with the industry, has evaluated 
the suitability of ferrous scrap from raw refuse as a raw material for exist- 
ing detinning operations. Tests ranged from in-house, laboratory-scale 
detinning to full-scale commercial detinning arranged for and conducted by a 
commercial detinner. The significant results are summarized as follows: 

1. It is technically feasible to reduce surface tin on refuse-derived 
scrap to levels as low as 0.01 pet, on a thoroughly rinsed detinned product. 



48 



2. On a practical commercial scale, final tin content will include a combina- 
tion of tin unleached from the surfaces and solder seams, the tin-bearing solution 
that cannot be completely rinsed off, and tin from solution carried out through 
absportion in paper, fabric, and wood. 

3. Unleached tin can be minimized by reshredding the scrap without balling. 
This achieves greater dislodging of lacquer coatings and rupturing of seams. 
Shredding also allows for freer flow of the detinning solution and more thorough 
draining after detinning. 

4. Solution carryover is minimized by combining air classification and mag- 
netic separation with shredding. This removes combustibles and dirt which absorb 
caustic solution and reduce metallic yield. 

5. Preliminary results from 10- ton lots indicate that the primary objective in 
the commercial-scale test of achieving a tin residual of 0.06 pet maximum was 
attained. 

6. Additional phases of the 150- ton test will establish optimum preparation 
steps for the ferrous scrap from municipal refuse and demonstrate steel quality 
in production melts. 



TABLE 2. - Examples of commercial scrap quality 



Type of scrap 



No . 1 heavy melting 

No . 1 factory bundle 

Shredded autos 

Detinned bundle 1 (revert, 

prompt industrial) 

No. 2 bundle (non-auto).. 
No . 2 bundle (auto) 



Base steel 



Cu Sn 



0.16 
.06 
.22 

.38 
.48 
.03 



Chemical composition, pet 



0.001 
.005 
.021 

2 .04 
.038 
.08 
.009 



Cr Ni 



0.05 
.04 
.16 

C 1 ) 

.10 
.12 
.02 



0.08 
.04 
.10 

( X ) 
.08 
.10 
.02 



Mo 



0.028 
.03 
.02 

( X ) 
.02 
.02 
.001 



Pb 



NA 

NA 

0.01 

( X ) 

NA 
NA 

NA 



0.015 
NA 
.023 

( X ) 
.012 
NA 
.011 



NA Not available. 

NAp Not applicable. 

detailed analysis not available 

of the base steel. 
2 Typical range = 0.036 to 0.048 pet. 
3 Analysis of base steel used for canmaking (Bethlehem Steel Corp 

communication) . 



0.025 
.025 
.039 

(!) 
.048 
.08 
.024 



Yield, 
pet 



90-94 
88-91 
92-94 

90 
84-86 
76-87 
NAp 



Bulk 

density, 

lb/ft 3 



NAp 

75 min. 
50-110 

120-160 
75 min. 
100 
NAp 



Other elements assumed to be comparable to that 



private 



TABLE 3, 



- Composition of ferrous samples from 10-ton lots, pet 



Component 



Tin-plated cans 

Bimetal tin-plated cans 

Bimetal tin-free cans 

Bottle and jar caps 

Paperboard containers with metal ends .' 

Miscellaneous magnetics 

Loose combustibles 

NA Not available. 

^10-ton lot subsequently air-classified and magnetically separated. 
10-ton lot subsequently reshredded, air-classified, and magnetically separated. 



Lot 1 J 



49.6 


46.1 


2.4 


2.9 


15.8 


17.0 


2.1 


2.7 


NA 


. NA 


29.2 


30.3 


.8 


1.1 



Lot' 



49 

It can be concluded from evaluations to date that ferrous scrap from municipal 
solid waste can be commercially detinned to an acceptable level with proper scrap 
preparation. The preparation must remove as much contamination as possible (organics, 
combustibles, nonferrous metals). The processing must also open whole cans as much 
as possible to allow the solution to circulate freely and drain upon removal from 
the tank. Finally, an effective method of processing to accomplish the desired 
preparation follows: Reshredding the scrap, air classifying to remove light organ- 
ics and combustibles, then magnetically separating the scrap to eliminate any 
unwanted heavy nonmagnetic material such as wood and nonferrous metal. This method 
is similar to that recommended by the Bureau of Mines on its scaled-up flowsheet for 
raw refuse processing (7) . 

References 

1. Committee of Tin Mill Products Producers, American Iron and Steel Institute 

(Washington, D.C.). Steel in Packaging. TM 650-676-20M-AP, 1977, p. 12. 

2. Duckett, E. J. The Influence of Tin Content on the Reuse of Magnetic Metals 

Recovered From Municipal Solid Waste. Resource Recovery and Conservation, 
v. 2, 1976-77, pp. 301-328. 

3. Gay, J. Scrap Recycling as Related to Electric Furnace Melting and Continuous 

Casting. Pres. at Ann. Meeting, AIME, Dallas, Tex., February 1974. 

4. Henny, J. J. Updated Cost Evaluation of a Metal and Mineral Recovery Process 

for Treating Municipal Incinerator Residues. BuMines IC 8691, 1975, 44 pp. 

5. Hogan, W. T., and F. T. Koelble. Purchased Ferrous Scrap — U.S. Demand and 

Supply Outlook. Study Prepared for American Iron and Steel Institute by the 
Industrial Economics Research Institute, Fordham Univ., New York, June 1977, 
p. 37. 

6. Ostrowski, E. J. Recycling of Tin-Free Steel Cans, Tin Cans and Scrap From 

Municipal Incinerator Residue. Iron and Steel Engineer, v. 48, No. 7, 
July 1971, p. 66. 

7. Phillips, T. A. An Economic Evaluation of a Process to Separate Raw Urban 

Refuse Into Its Metal, Mineral and Energy Components. BuMines IC 8732, 
1977, 25 pp. 

8. Sawyer, J. W. Automotive Scrap Recycling: Processes, Prices and Prospects. 

Published by Resources for the Future, Inc., distributed by The Johns 
Hopkins University Press, Baltimore, Md., and London, 1974, p. 32. 

9. Silver, J., P. J. Koros, and L. R. Shoenberger. The Effect of Use of Bundled 

Auto Scrap on Sheet Steel Quality. Pres. at 42d Ann. Conv., Institute of 
Scrap Iron and Steel, Inc., Los Angeles, Calif., Jan. 20, 1970. 

10. Sullivan, P. M. , and H. V. Makar. Bureau of Mines Process for Recovering 

Resources From Raw Refuse. Proc. 4th Miner. Waste Utilization Symp., 
cosponsored by the Bureau of Mines and IIT Research Institute, Chicago, 111., 
May 7-8, 1974, pp. 128-141. 

11. . Quality of Products From Bureau of Mines Resource Recovery Systems 

and Suitability for Recycling. Proc. 5th Miner. Waste Utilization Symp., 
cosponsored by the Bureau of Mines and IIT Research Institute, Chicago, 111., 
Apr. 13-14, 1976, pp. 223-233. 

12. U.S. Environmental Protection Agency. Fourth Report to Congress: Resource 

Recovery and Waste Reduction. SW-600, 1977, 142 pp. 



50 



MONROE COUNTY RESOURCE RECOVERY FACILITY 

by 
D. B. Spencer 1 



The Monroe County (N.Y.) Resource Recovery Facility (RRF) is designed to 
process municipal, commercial, and light industrial waste at a rate of approxi- 
mately 127 metric tons per hour (140 tph) , figure 1. Two fully identical pri- 
mary process lines will extract ferrous metals and a light paper fraction 
which will be burned as a supplementary fuel in utility boilers for power 
generation or, alternatively, reclaimed as paper in the future. 

The process that will be utilized was developed by Raytheon and is based 
heavily on experimental work performed by Raytheon and the U.S. Bureau of 
Mines (USBM) at the USBM Raw Refuse Processing Pilot Plant in Edmonston, Md., 
under a cooperative agreement for testing and scale-up of resource recovery 
technology. Similar to operations at the USBM plant, shredding and air classi- 
fication will be performed in multiple states in the Monroe project. In addi- 
tion, however, it is planned to utilize a rotary-drum air classifier and 
nonferrous metal separator developed independently by Raytheon Co. and Iowa 
Manufacturing Co., a Raytheon subsidiary engaged in the manufacture of heavy 
process machinery. 

Establishing product quality and confidence levels and market development 
have been key parts of the work performed on this project. This has included 
testing sample products over a wide range of pilot plant tests, optimizing 
processing techniques to improve product quality, and testing sample products 
by potential users in their own operations. 

A 20-year agreement has been reached between Monroe County and Rochester 
Gas & Electric Co. (RG&E) for purchase of the RDF product. This agreement 
requires RG&E to utilize as much fuel as is possible up to the maximum avail- 
able from the facility and to pay 100 pet of the net value of coal saved after 
adjustments for all incremental costs incurred by RG&E for cofiring of RDF 
with pulverized coal. 

Raytheon has negotiated firm agreements for sale of the glass to Owens- 
Illinois, the aluminum to Reynolds Metals, and the ferrous metals to Vulcan 
Materials. All these agreements are tied to market indices, have floor 
prices, and are for 5 years from the date of full commercial operation of 
the facility. 



Project manager, Raytheon Service Co., Burlington, Mass. 



51 




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52 



PROMISING APPLICATIONS FOR MUNICIPAL INCINERATOR RESIDUES 

by 
R. J. Collins 1 



Incineration is a principal means of solid waste disposal in many metro- 
politan areas of the United States. The primary advantage of incineration is 
that it reduces the volume of incoming solid waste by 80 to 90 pet, thus 
extending the life of existing landfills. Nevertheless, a residue is produced 
after burning, which represents from 20 to 40 wt-pct of the original refuse. 
The residues are a soaking wet mixture of glass, metals, ash, minerals, and 
combustible matter and must be disposed of in an environmentally acceptable 
manner . 

There are approximately 140 municipal incinerator plants currently in 
operation throughout the United States. These plants generate a combined 
total of 5 million tons of incinerator residue annually (3) . Although incin- 
erators are located in 24 States and the District of Columbia, the largest 
concentration of plants is found in the Northeast, particularly in Connecticut 
and New York. 

Incinerator residue is a heterogeneous material derived from the combus- 
tion of municipal refuse. Essentially, municipal refuse is composed of a 
combustible fraction (paper, food wastes, wood, textiles, yard wastes, etc.) 
and a noncombustible fraction (metals, glass, ceramics, bricks, rocks, etc). 
Although the composition and moisture content of refuse does vary during dif- 
ferent times of the year and in different parts of the country, the combusti- 
ble fraction normally represents 60 to 80 wt-pct of the incoming refuse (2) . 

The proper combustion of solid waste in municipal incinerator plants is 
influenced by three basic factors: Time, temperature, and turbulence. The 
refuse must be exposed to temperatures of 1,600° to 1,800° F long enough for 
satisfactory combustion. In general, the more the refuse is agitated during 
burning, the higher the degree of burnout. 

Degree of burnout can be defined as the ratio of the incinerated refuse 
to the combustible fraction of the refuse. It is dependent primarily on the 
type of incinerator furnace and the grate system used for feeding refuse 
through the incinerator, although differences in plant operation also affect 
burnout. For practical purposes, municipal incinerator residues can be 
broadly classified into three categories, based on degree of burnout, as 
follows: 

1 - Well-burned-out .—These residues comprise approximately 10 vol-pct 
and 20 to 30 wt-pct of refuse input (1) . 



Executive vice president, Valley Forge Industries, Inc., Devon, Pa. 



53 



2. Intermediately burned-out . — These residues usually represent approxi- 
mately 20 vol-pct and 25 to 35 wt-pct of refuse input (1_) . 

3. Poorly burned-out . — These residues comprise about 30 to 40 wt-pct of 
the refuse input (1) . 

Municipal incinerator residues, although heterogeneous in nature, are 
predictable in their composition and gradation. Past experience and the 
results of extensive study have shown that these residues are suitable for 
use in embankments, landfills, subbases, stabilized base courses, and bitumi- 
nous paving mixtures with a minimal amount of processing. Well-burned or 
intermediately burned residues are acceptable for such uses. Some aging is 
recommended for all residues prior to use. Extended aging for 6 to 12 months 
is needed to improve the characteristics of poorly burned residues. 

At present, the use of residue in bituminous paving appears to be the 
most promising application of this material. Residue use is more highly 
recommended in base course applications. The residue should be blended on 
an equal -weight basis with natural aggregate. The addition of hydrated lime 
is also required to improve asphalt adhesion. Residue paving mixtures can 
be mixed, spread, and compacted using methods and equipment normally employed 
in conventional asphalt paving. 

Some consideration should also be given to the use of incinerator residue 
as a synthetic aggregate through heat fusion and in the production of struc- 
tural brick and mineral wool insulation. The energy requirements and eco- 
nomics associated with each of these applications must be carefully 
investigated. 

References 

1. Achinger, W. C, and L. E. Daniels. An Evaluation of Seven Incinerators. 

Proceedings, 1970 National Incinerator Conference. American Society 
of Mechanical Engineers, New York, 1970, pp. 32-64. 

2. Niessen, W. R., and S. H. Chansky. The Nature of Refuse. Proceedings 

1970 National Incinerator Conference. American Society of Mechanical 
Engineers, New York, 1970, pp. 1-31. 

3. Pindzola, D., and R. J. Collins. Technology for Use of Incinerator 

Residue as Highway Material. Identification of Incinerator Practices 
and Residue Sources. U.S. Dept. of Transportation, Federal Highway 
Administration, Report FHWA-RD-75-81, Washington, D.C., July 1975, 
77 pp. 



54 



FIBER RECOVERY FROM MUNICIPAL SOLID WASTE 

by 

G. M. Savage, 1 L. F. Diaz, 1 
and G. J. Trezek 1 



Depletion of our national forest reserves coupled with an increasing pub- 
lic reluctance to allow the opening of new timber areas to harvesting has 
resulted in a decreased supply of the basic raw material for pulp and paper 
production, namely wood. One consequence of this dwindling supply is rising 
prices for lumber as well as for paper products. In addition to the poor 
economic consequences, the harvesting of vast regions of timber may pose 
serious climatological consequences. Evidence is available that supports the 
contention that destruction of forests has a deleterious effect on the carbon 
dioxide balance of the atmosphere, with the net effect being the possibility 
of altering the world climate (3) . 

As an alternative to the use of forest lands for securing the raw mate- 
rial for pulp and paper production, the possibility exists for exploiting a 
heretofore-untapped source of cellulosic fiber; that is, the paper fiber 
present in solid waste presently being landfilled. In this paper the means 
of recovering paper fiber from this refuse will be explained. At the same 
time the properties of handsheets formed from fiber recovered from solid waste 
will be presented and compared with those of other types of wastepaper. 
Successful and efficient recovery of fiber from the municipal solid waste 
stream requires an encompassing management plan ranging from solid waste 
processing to pulp mill technology. We have examined fiber recovery from 
the standpoints of refuse collection, mechanical preprocessing, hydropulping, 
cleaning, water treatment, and determination of recovered pulp properties. 

As previously reported by Trezek and Golueke (2) , experiments conducted 
at the Richmond Field Station of the University of California (Berkeley) have 
shown that fiber recovery from municipal solid waste is technologically feas- 
ible provided that a certain processing sequence is followed. The overall 
system consists of a dry process followed by a wet process, which includes 
water. 

The main components of the dry processing are (1) a hammermill grinder 
(rated at 10 tons per hour), (2) a vertical air classifier, (3) a cyclone and 
air-lock feeder, and (4) a rotary cylindrical screen (trommel) . The system 
is capable of processing up to 4 tons of refuse per hour and typically pro- 
duces a wastepaper fraction in the range of 40 to 60 wt-pct of the input total. 
The wastepaper serves as a feedstock for the wet processing system. The per- 
centage of the raw waste that is recovered as wastepaper fraction is dependent 
upon the type of waste being processed; that is, residential or commercial. 
The processing sequence has succeeded in reducing the water quality problems 
associated with the pulping of refuse-derived pulp so that conventional 

All of the authors are with the University of California, Berkeley, Calif. 



55 



waste-water treatment can be employed. Fiber recovered from residential solid 
waste exhibits strength characteristics similar to those of 100-pct-deinked 
newspapers and virgin groundwood. On the other hand, fiber recovered from 
commercial solid waste possesses slightly greater strength properties, similar 
to those of a typical newsprint furnish of groundwood and chemical pulp. 

The cellulosic content of urban solid waste is considerable. Presently, 
some 2 million tons of paper per year are landfilled in the San Francisco area 
alone (1_) . Given the technical means as described here for fiber recovery, 
the solid waste stream can be viewed as a resource to be exploited. It is 
hoped that this research will stimulate the recovery and utilization of fiber 
from solid waste. Not only would fiber recovery reduce energy and raw mate- 
rial expenditures within the pulp and paper industry, but the present disposal 
problem of postconsumer fiber would be greatly reduced or eliminated. 

References 

1. Diaz, L. F., G. M. Savage, R. P. Goebel, G. C. Golueke, and G. J. Trezek. 

Market Potential of Material and Energy Recovered From Bay Area Solid 
Wastes. Report prepared for State of California Solid Waste Management 
Board, March 1976. 

2. Trezek, G. J., and C. G. Golueke. Availability of Cellulosic Wastes for 

Chemical or Bio-Chemical Processing. AIChE Symposium Series 158, 
Bio-Chemical Engineering — Energy, Renewable Resources and New Foods, 
v. 72, 1976. 

3. Woodwell, G. M. The Carbon Dioxide Question. Sci. American, v. 238, 

No. 1, 1978, p. 34. 



56 



RECOVERY OF GLASS FROM URBAN REFUSE BY FROTH FLOTATION 

by 
J. H. Heginbotham 1 



As part of its research program, the Bureau of Mines, U.S. Department of 
the Interior, investigates new or improved metallurgical technologies that are 
needed to help maintain adequate material and metal supplies while conserving 
natural resources through the recovery of values from secondary resources such 
as urban refuse. A process was devised and a pilot plant was constructed to 
reclaim valuable materials from the residues of municipal incinerators (2) . 
Products from the primary section of the pilot plant include clean ferrous 
scrap, mixed nonferrous metals, and glass aggregates. A major portion of 
the current flowsheet is shown in figure 1. 

Following development of the incinerator residue system, a companion 
process was developed and a pilot plant constructed to recover materials from 
unburned urban refuse (4) . Products reclaimed in this pilot plant include 
ferrous scrap, aluminum, mixed heavy nonferrous metals, glass aggregates, and 
combustibles for use as fuel (3) • A major portion of the raw refuse flowsheet 
is shown in figure 2. 

Glass aggregates recovered in both systems contain approximately 10 pet 
nonglass materials (principally ceramics, brick, and stones), making the 
products unsuitable for use as cullet in the manufacture of glass containers. 
To be acceptable for use as cullet, glass recovered from urban waste must meet 
a rigid set of specifications that has been imposed by the glass container 
industry (1) . The most critical requirement involves the permissible number 
of refractory particles that can be tolerated in a specified quantity of 
cullet. The minus 20- plus 40-mesh fraction of a 1-pound sample of cullet 
(minus 20- plus 150-mesh) , in which there are an estimated 600,000 particles, 
cannot contain more than 2 refractory particles, and the minus 40- plus 
60-mesh fraction cannot contain more than 20 particles. 

The specifications include the statement, "for the purpose of evaluating 
cullet coming from a municipal resource recovery system, these particles will 
be considered refractory until the glass container manufacturer can certify 
otherwise." The particles referred to are foreign particles in a 1-pound 
sample of cullet that are separated from the glass by heavy liquid at 2.65 
specific gravity. Corundum, mullite, zircon, chromite, spinel, sillimanite, 
andalusite, kyanite, and cassiterite are listed as being refractory in sizes 
larger than. 60 mesh. Ceramic ware, vitreous clay, chinaware, bricks, tile, 
gravel, and concrete fragments are objectionable since they can result in 
partially fused inclusions in the finished glass. Metallic aluminum, radio 
tube parts, spark plug porcelain, chrome ore, or chrome refractory in any 
amounts are the most objectionable cullet contaminants. 



Metallurgist, Avondale Research Center, Bureau of Mines, Avondale, Md. 



57 



REVOLVING SCREEN 
l-l/4-inch holes 



FEED CONVEYOR 





»5 SAN 



SCREEN 
1/4- inch ond 20- mesh 
SAND PUMP 



r^J 



HAMMER MILL 



- Large moqnetic iron 
(cans, etc) 



SCREW CONVEYOR 



Minus 20-mesh Filter 
sands cake 
\>~s f VACUUM PUMP. 




TERTIARY SCREEN 
1/4-inch top deck 
20-mesh Bottom deck 



Nonferrous metals 



SAND PUMP 



CIRCULATING 
WATER PUMP 



SCREW CONVEYOR 



DEWATERING 
CLASSIFIER 



Light fraction 
to waste 



MINERAL JIG 
2 compartments 



Heavy slag 



Recirculating 
water 



Fine gloss aggregate 
to flotation circuit 



HEAVY METAL 

SEPARATION 

UNIT 



Aluminum 
Heavy metols 



ELECTROMAGNETIC 
SEPARATOR 



DEWATERING JqI DRUM Sl 
CLASSIFIER f**\ 

j ^ Mognetics, 

!^7 — . minus 1/4 in 




ROLL 
CRUSHER (OS\ 

i 



Heavy metal removed periodically 

g 



v 

Fine sla 




SCREEN, 8-mesh 

Aluminum metal 



SAND PUMP 



FIGURE 1. - Municipal incinerator residue recovery flowsheet. 

Even though these specifications were not available during the early 
years of research on incinerator residues, it was evident at that time that 
the minus 20-mesh aggregate remaining from nonferrous metal recovery opera- 
tions would not be suitable for use as cullet. Pioneering research was begun 
to determine whether a clean glass product could be prepared using conven- 
tional minerals benef iciation technology, specifically froth flotation. The 
principal objective at that time was to obtain a marketable product by float- 
ing all of the nonglass material away from the glass. Test results gave no 
real evidence of success for this approach, and the test program was recessed. 

In 1970 testing was resumed with the new objective of floating glass 
away from all nonglass materials. From the start, it was evident that this 
approach had potential for success, and by mid-1972 results were so encourag- 
ing that a decision was made to add a glass flotation section to the pilot 
plant operations . 



58 



Unburned refuse 



PRIMARY 
SHREDDER 



key; key: 

I ^> Air to baghouse 

■^taB Water to recycle 
system 



LIGHT AIR 
CLASSIFIER 



Very light paper 
and plastic 



MAGNETIC 
SEPARATOR 



Magnetic metal 
to detinning 



Nonmagnetics 



PRIMARY 

AIR CLASSIFIER 

/ / 



Massive metals 



MAGNETIC 
SEPARATOR 



I 

Glass, nonferrous metals, 

and heavy organics 
with paper and plastics 





C=> 



C=> 



COMPACTOR 



Heavy 


Heavy 


iron 


nonferrous 




metal 



Z^s~" ■ with paper a 

1 r-l 



TROMMEL 



Aluminum and 

heavy organics > 

with paper and 

plastics 



I 

■ -» Alternate — ^ 

_f_ 



SECONDARY 
SHREDDER 



TROMMEL 



Glass, nonferrous metals, 
heavy food,and other organics 




Organic 
wastes 



MINERAL 
JIG 



SECONDARY AIR 
CLASSIFIER 



"!—►- Coarse gl 



ass 
aggregate 



Heavy 
nonferrous metals 



Fine glass 
aggregate 



Aluminum and 
heavy organics 

t 

I ELECTROSTATIC I 
♦ SEPARATOR I 



Light paper 
and plastics 



Fine glass 
and dirt 




t=> 



Paper and plastic 



Aluminum 



Heavy 
organics 



COMPACTOR 



Paper and plastics 



To flotation 
circuit 



FIGURE 2. - Raw refuse separation flowsheet. 



sav thafthP Z 8ained /j° m pilot P^ ant operations (fig. 3) makes it unsafe to 
tZ ^ the , day 7^ n and da r° Ut Paction of flotation concentrates will meet 
the stringent gullet specifications in continuous operations; that is, this is 
Mill f 6 eX1S " ing la <* °f P reclse quality-control methods, the human falli- 

lll °f operators, and the inaccuracies that are possible with current 
methods of product evaluation. 



59 



Glass aggregate feed 



Plus 20 mesh 



Minus 20 mesh 



Water 



KEY 

1. Impact crusher 

2. Roll crusher 

3. Circular vibrating screen 

4. Vibrating feeder and hopper 

5. Centrifugal pump 

6. No. 1 desliming classifier 

7. No. 2 desliming classifier 

8. Flotation cells 

3 rougher cells 
1 cleaner cell 

9. No. 2 cleaner cell 

10. No. 3 cleaner cell 

11. Filter 

12. Dryer 

13. Induced roll magnetic separator 

14. Centrifugal pump 



Water 



Water 



Reagents 



J-J 



70 



Slime discard 



■ mma ' !."- 



discard 



Cleaner tailings 




M« 



11 

Recycle water 



Jkn 



Final glass concentrate 



Magnetic tailings 



FIGURE 3. - Flowsheet of continuous glass flotation section. 



60 



It has been demonstrated by batch and continuous testing, (table 1) that 
cullet-quality glass products can be recovered from solid waste streams by 
froth flotation. The technology and equipment involved have been highly 
developed in the minerals industry. The glass product of this technology is 
untried commercially, but the fact that three resource recovery plants are now 
under construction that will use froth flotation in glass recovery systems 
demonstrate confidence in the emerging resource recovery industry that this 
product can be used to make new glass containers. 

TABLE 1. - Summary of pilot plant operations 



Product 



Slime discard 

Flotation tailings.... 
Flotation concentrates 
Composite, 



Wt-pct 



11.3 

16.2 

70.3 

100.0 



Glass 



pc 



tl 



90.0 
40.0 
99.9 
88.9 



Glass 

distribution, 

pet 



13.7 

7.3 

79.0 

100.0 



Glass content of all products was either estimated or calculated. 



References 

1. Glass Packaging Institute. GCMI Specifications for Glass From Resource 

Recovery Systems. Suite 400, 1800 K St., NW, Washington, D.C. 20006, 
Jan. 14, 1976. 

2. Henn, J. J. Updated Cost Evaluation of a Metal and Mineral Recovery 

Process for Treating Municipal Incinerator Residues. BuMines IC 8691, 
1975, 44 pp. 



4. 



• Quality of Products From Bureau of Mines Resource Recovery Systems 

and Suitability for Recycling. Proc . 5th Mineral Waste Utilization Symp., 
cosponsored by the Bureau of Mines and IIT Research Institute, Chicago, 
111., Apr. 13-14, 1976, pp. 223-233. 

Sullivan, P. M., and H. V. Makar. Bureau of Mines Process for Recovering 
Resources From Raw Refuse. Proc. 4th Mineral Waste Utilization Symp., 
cosponsored by the Bureau of Mines and IIT Research Institute, Chicago, 
111., May 7-8, 1974, pp. 128-141. 



61 



TEST PROCEDURES FOR DETERMINING THE GROSS CALORIFIC VALUE OF REFUSE 
AND REFUSE-DERIVED FUELS BY OXYGEN BOMB CALORIMETRY 

by 

D. R. Kirklin, 1 D. J. Mitchell, 1 J. Cohen, 1 E. S. Domalski, 1 

and S. Abramowitz 1 



The recovery and utilization of energy from solid waste have been the 
subject of much interest since concern is being expressed about our fuel 
shortages. Fossil fuels are presently being used in powerplant boilers to 
generate steam for energy purposes. Solid waste is a potential source of fuel 
that can be utilized in powerplant boilers to generate steam for energy pur- 
poses. Therefore, much research is centered around the conversion of solid 
waste to energy. Before solid waste can be effectively utilized in powerplant 
boilers, much testing is necessary. The areas of solid waste analysis, ash 
analysis, emission testing, corrosion testing, and boiler performance are of 
primary concern. 

The American Society of Mechanical Engineers (ASME) Committee for Per- 
formance Test Code 33 — Large incinerators (PTC-33) has indicated that a need 
exists to find a more accurate test procedure for the determination of calo- 
rific values of refuse and refuse-derived fuels (RDF) that will more accu- 
rately represent a corresponding large array of collected raw refuse. If an 
improved calorific value test procedure is available to the ASME PTC-33 com- 
mittee, it can offer a mechanism by which public works administrators and 
private owners can evaluate with greater accuracy and higher confidence than 
is presently possible whether or not their large incinerators and refuse-fired 
boilers are in compliance with their contract performance specifications. The 
E-38 Committee on Resource Recovery of the American Society of Testing and 
Materials (ASTM) is interested in establishing refuse-derived fuels (RDF) as 
an article of commerce. A laboratory procedure giving reproducible results 
will better equip commercial laboratories to certify accurately the energy 
content of RDF of various compositions. As an article of commerce, RDF can 
be bought and sold as a regulated low-sulfur fuel to supplement other fossil 
fuels. The U.S. Environmental Protection Agency (EPA) and the U.S. Department 
of Energy (DOE) are collaborating in resource recovery programs to facilitate 
the development of various waste-to-energy technologies. The need for infor- 
mation on the calorific value of waste streams has been acknowledged by 
incinerator operators and designers. 

The quantity of energy liberated per unit mass of refuse burned (gross 
calorific value of refuse) can be directly obtained from a bomb calorimetric 
experiment. The techniques of bomb calorimetry are well characterized (4.-5) . 
Bomb calorimetry is used extensively in the determination of the calorific 
value of various fossil fuels (1). Therefore, it would be extremely advan- 
tageous to be able to accurately determine the calorific value of refuse and 
RDF by bomb calorimetric methods. 

X A11 of the authors are with the National Bureau of Standards, Washington, D.C, 



62 



However, municipal refuse is far from being an easily characterized homo- 
geneous fuel. Its makeup can vary widely, depending upon many geographical, 
seasonal, and weather-related factors. This variability will affect both a 
refuse stream's potential as a fuel source and its potential as a source of 
environmental pollution. 

The objectives of the research program are threefold: 

1. Development of test procedures to determine the gross calorific value 
of refuse and RDF by bomb calorimetric methods . 

2. Evaluation of sample characteristics by analyzing for moisture, ash, 
carbon, sulfur, and chlorine. 

3. Evaluation of the homogeneity and sample preparation requirements for 
bomb calorimetric experiments utilizing two bomb calorimeters which have capa- 
bilities for handling samples that differ by an order of magnitude in mass 
Cthat is, 2.5 g and 25 g) . 

Refuse has five forms: (1) As-received refuse with the "white goods" 
removed ("white goods" are items such as refrigerators, stoves, and sinks); 
(2) shredded refuse of 2.5 to 7.5 cm (1 to 3 inch) particle size; (3) shredded 
refuse with the "heavy fraction" removed ("heavy fraction" is the noncombusti- 
bles such as glass and ceramics); (4) refuse pellets; (5) refuse powder. 
Forms 3, 4, and 5 are considered RDF. The sample preparation required to pre- 
pare a bomb calorimetric sample from any of the five forms is such that the 
bomb calorimetric sample is definitely an RDF. In fact, the preparation of 
a homogeneous sample for a calorific determination (regardless of the tech- 
nique to be utilized) is the processing of an RDF of some degree. Therefore, 
the initial testing performed in this research project started with forms 4 
and 5. 

Materials used in the program were a standard reference sample of benzoic 
acid obtained from the National Bureau of Standards, Ultra High Purity-grade 
oxygen from Matheson Gas Products, Teledyne National RDF, and Combustion 
Equipment Associate RDF (ECO-II RDF) . 

Results on a limited number of samples have demonstrated that RDF samples 
can be processed for bomb calorimetric experiments to produce results with a 
precision (standard deviation of a measurement) approximately equal to or 
better than 1 pet. The calorific values 2 determined at three stages of sample 
preparation showed no overwhelmingly significant differences. For Teledyne 
National samples, the calorific values slightly increased with increased 
sample processing, but opposite trends were observed for ECO-II samples. 
Moreover, the percent deviation (for moisture- and ash-free RDF) based on 
all three types of samples was 0.802 pet for Teledyne National RDF and 

2 



Owing to the arbitrary selection of the RDF field samples, the precision 
obtained by the reported procedures is the most significant result. In no 
way does NBS imply that the experimental results presented are typical of 
the average stream of the RDF's tested. 



63 

0.424 pet for ECO-II RDF. Percent deviations between two types of either 
Teledyne or ECO-II RDF's ranged from 0.21 to 0.94 pet. 

Our standard deviations of a measurement are much less than one would 
initially expect for something as nonhomogeneous as refuse. This was achieved 
by using the amount of combustion residue of each experiment to calculate an 
MAF calorific value rather than an average ash value. For some RDF samples 
the ash values are not constant. Noncombustibles must "stick" to RDF parti- 
cles and are therefore not uniformly distributed throughout the RDF samples. 
Therefore, a more precise ash-free heating value can be calculated using the 
amount of ash contained in each combustion sample. 

Coals of various ranks have typical moisture- and ash-free (MAF) gross 
heating values (2-3) ranging from 34.89 to 25.59 MJ kg" 1 (15,000 to 11,000 
Btu lb -1 ). Our MAF-RDF results ranged from 25.20 to 21.93 MJ kg" 1 (10,835 
to 9,427 Btu lb -1 ). Our results are based upon two 20-kg (44-pound) field 
samples of RDF, which automatically makes it impossible to evaluate whether 
our results 3 are typical of the RDF's produced by either manufacturer. How- 
ever, RDF's calorific value makes it definitely a viable competitor of some 
low-rank lignites. Also bituminous coals typically demand a greater degree 
of fineness than low rank coals to achieve complete carbon burnout (3) . The 
necessary degree of fineness for RDF's may even be less (that is, larger 
particles) than that for the low-rank coals. 

All fuels contain mineral matter that goes through varying stages of 
decomposition and recomposition in the combustion process. It all ends up 
either as bottom ash or fly ash. Coal may have ash contents of the order of 
10 pet, compared with the 12 pet values we experienced with RDF. However, ash 
fusibility data re necessary to properly evaluate the ash problem presented by 
refuse and RDF. 

Reference s 

1. American Society of Testing and Materials. Standards D240, D2382, D2015, 

and D3286 in 1977 Annual Book of ASTM Standards. Philadelphia, Pa., 1977. 

2. . Standard D388 in Annual Book of ASTM Standards. Philadelphia, Pa., 

1977. 

3. Burbach, H. E., and D. A. Harris, R. P. Hensel, 0. Martinez, and 

G. W. Thimot. Power, v. 121, 1977, p. 41. 

4. Jessup, R. S. Precise Measurement of Heat of Combustion With a Bomb 

Calorimeter. NBS Monograph 7, 1960. 

5. Prosen, E. J. Ch. 6 in Experimental Thermochemistry, ed. by F. D. Rossini. 

Interscience Publishers, New York, 1956. 



3 See footnote 2. 



64 



OPERATING ECONOMICS OF THE CITY OF AMES RESOURCE RECOVERY SYSTEM 

by 
S. H. Russell 1 and M. K. Wees 1 



The Ames, Iowa, resource recovery system, which processed an average of 
186 tons per working day in 1977, is shown in schematic form in figure 1. The 
refuse is processed by two stages of shredding, magnetic removal of ferrous 
metals, air density separation, and nonferrous metals separation. The metals 
are sold, and the refuse fuel is stored, then fired as a supplement to coal in 
the city-owned powerplant. Details of the system's equipment have been pre- 
sented in other references (1.-2) . Startup and equipment shakedown began in 
September 1975. 

After startup, the system's design engineering firm (Henningson, Durham & 
Richardson) began an operations monitoring program. Information was scarce 
during the first few months of operation, because the city's accounting system 
for the new municipal entity had not yet been finalized. As more information 
became available, the calculations and reporting became more complex. A 
computer-based management information system (MIS) has therefore been devel- 
oped to aid in operations monitoring. Operating data are entered (or changed) 
and reports are generated with an interactive computer program which requests 
the required information with a series of questions in English. This feature 
allows for use of the MIS by persons not familiar with the programing, or even 
by persons unfamiliar with computers. 



« (p. FLOW ORIFICE 




FERROUS STORAGE 



FIGURE 1. - Schematic of Ames resource recovery system. 



Environmental engineers, Hennington, Durham and Richardson, Omaha, Nebr. 



65 



The following is a discussion of results obtained after running the unit 
for the year 1977. Data were obtained through the use of the MIS. 

Materials Balance 

Over 48,000 tons of solid waste was processed by the system in 1977, 
which is an average of about 4,000 tons per month, or 186 tons per working 
day. About 3,000 tons of ferrous metals (6.2 pet of total waste stream) were 
sold at an average of $31.5 per net ton before transportation charges during 
the year. Almost 84 pet of the total was converted to fuel with an average 
value of about $1.15 per million Btu. Smaller amounts of other materials 
were recovered. 

Energy Balance 

About 2.8 million kwhr was consumed by processing, storing, and conveying 
the refuse (an average of about 60 hwhr/ton processed), while about 19.3 mil- 
lion kwhr was produced from burning the prepared fuel. This represents an 
average out-in ratio of 7:1 (a low of 4:1 and a high of 10:1). 

Costs 



$100 

for 

year 



-NET FACILITY COST 



TONS PER MONTH 



Total facility costs for the year were about $1.1 million (which includes 

,000 in startup cost repayment), or about $22.70 per ton. Total revenues 

the year were about $460,000, or about $9.50 per ton. Net costs for the 

were about $640,000, which translates to $13.20 per ton. Figure 2 shows 

the incoming tons and net 
facility cost by month for 
1977. 

The Ames resource recov- 
ery system may be of inter- 
est to those starting 
resource recovery systems 
in other cities. With 
appropriate modifications, 
the Ames MIS could be used 
to monitor other supplemen- 
tal fuel systems, processed- 
fuel steam systems, or mass- 
fired steam systems. The 
MIS provides a permanent 
record of the most important 
operating characteristics of 
a solid waste energy and 
materials recovery system 
along with various methods 
of data reporting. 




-3000 5 



FIGURE 2. 



MONTH (1977) 

Costs by month for 1977. 



66 



The Ames solid waste recovery system has operated successfully and is 
presently in its third year of operation. Waste was diverted to the landfill 
for only 15 days during the year owing to scheduled and unscheduled downtime 
of the processing plant and the powerplant (an availability of over 94 pet) . 
Although higher than landfilling costs in the region, the costs of the system 
have been showing a downward trend. The cost per capita for operating the 
system during 1977 was about $10. After the 1979 operating year, the startup 
costs will have been repaid. The 1980 operating year will show a net cost 
decrease of about $2 per ton for this reason alone. 

References 

1. Funk, H. D., and S. H. Russell. Energy and Materials Recovery System, 

Ames, Iowa. Proc. 5th Miner. Waste Utilization Symp., cosponsored 
by the Bureau of Mines and IIT Research Institute, Chicago, 111., 
Apr. 13-14, 1976, p. 133. 

2. . Operating Experience of the Ames Solid Waste Recovery Plant. 

AICHE Symposium Series: Energy and Resource Recovery From Industrial 
Municipal Solid Wastes. American Institute of Chemical Engineers, 
New York, v. 73, 1977, p. 162. 



67 



TROMMEL PROCESSING OF MUNICIPAL SOLID WASTE PRIOR TO SHREDDING 

by 
J. F. Bernheisel, 1 P. M. Bagalman, 2 and W. S. Parker 3 



Shredding has been traditionally regarded as the first step in processing munic- 
ipal solid waste (MSW) for recovery of materials and energy. The facilities con- 
structed in the last decade have generally taken this approach. The functions the 
shredder performs are two: (1) Reduction of material to a more uniform particle 
size, and (2) liberation of composites or entrapped materials. 

There are, however, drawbacks to shredding. First, shredders have high oper- 
ating and maintenance costs . These are primarily electrical energy consumption and 
the labor, energy, and materials associated with hammer retipping, balancing, and 
replacement. Further, shredding has deleterious effects upon subsequent resource 
recovery processes. Following shredding, the most common processing step is air 
classification. The idealized function of this is to produce two fractions: 
(1) An organic combustible fraction, and (2) an inorganic noncombustible fraction 
which can be processed for materials recovery. If the ideal were achieved, many 
of our current problems in resource recovery would be eliminated. However, the 
separation is far from ideal. Inorganic material reports with the organic fraction. 
The primary offender is glass and other fine-particle material . Some fine material 
is inherent in the solid waste; however, the greatest percentage is generated by the 
shredding process. The National Center for Resource Recovery has estimated that as 
much as 80 pet of the glass in MSW entering a shredder will be pulverized so as to 
fly in the air classifier. This, plus the fines inherent in MSW and the 8 to 10 
pet ash of paper and wood products, results in a refuse-derived fuel (RDF) with an 
ash of 25 pet or better. In addition, the glass that misreports in the air classi- 
fier is lost to recovery if glass recovery is to be attempted. 

To overcome the disadvantages discussed above, the design of the Recovery 1 
facility in New Orleans — a partnership among the National Center for Resource 
Recovery, the City of New Orleans, and Waste Management, Inc. — incorporated a 
trommel screen. This device, placed prior to the shredder, opens the refuse bags, 
both paper and plastic, breaks glass and other friable materials, and removes from 
the MSW those items that are smaller than the nominal screen size. In New Orleans, 
this is 4 inches . 

From the data developed by the testing in New Orleans, it can be concluded 
that the trommel achieves two of its design goals . It concentrates metals and glass 
for material recovery, and it enhances the quality of the potential refuse-derived 
fuel fraction. While there is a loss of potential fuel to the trommel underflow, 
it would appear that this would be acceptable in the many situations where lowering 
of the ash content is currently the primary concern. Further, the organics in the 
underflow are not lost and can be recovered by subsequent processing of the under- 
flow for materials recovery. In conclusion, the trommel appears to be a valuable 
new tool in the effort to recover resources from municipal solid waste. 

■^Testing program engineer. 
2 Demonstrator program manager, 
directing engineer. 

All of the authors are with the National Center for Resource Recovery, Inc., 
Washington, D.C. 



68 



UPGRADING PRODUCTS FROM RAW REFUSE FOR MARKETING 

by 

M. M. Cavanna, 1 J. S. Almarez, 1 
F. P. Christobal, 1 and H. G. Ramirez 1 



Research on recycling urban solid wastes in Spain is being performed by 
the Empresa Nacional Adaro de Investigaciones Mineras, S.A. (ENADIMSA) in 
Madrid. This firm belongs to the Instituto Nacional de Industria (INI), 
which is a division of the Ministry of Industry of Spain. ENADIMSA is mainly 
concerned with applied research in geology, hydrogeology, mining, and mineral 
dressing problems, as well as in environmental control, especially in regard 
to the recovery of raw materials from urban and industrial wastes. 

ENADIMSA' s research on raw refuse was started 5 years ago, under the 
Plan for Scientific and Technical Cooperation between Spain and the United 
States. 2 Very effective aid was obtained from the U.S. Department of the 
Interior, Bureau of Mines, Avondale (Md.) Metallurgy Research Center. The 
latter provided all the information and experience it had accumulated at that 
time. 

Research programs developed by ENADIMSA since that time have been con- 
ducted along the following three different lines of technology: 

1. Rough classification processes, figure 1. 

2. Upgrading operations, figure 2. 

3. Utilization of organic materials, figure 3. 

The work done on rough classification processes has been described in 
papers presented at the Fourth and Fifth Mineral Waste Utilization Symposiums 
and will not be further discussed here. The present paper describes details 
of the development of the next two lines of technology which complement the 
basic flowsheet previously exhibited for the rough classification process. 



All of the authors are with Empresa Nacional Adaro de Investigaciones 
Mineras, S.A., Madrid, Spain. 
2 A cooperative research agreement administered through the National Science 
Foundation and the Instituto Nacional de Industria. 



69 



Light fraction 



Trommel 



DOO OOOOO 
O O O o 

dooooooc 

O O ° O 

) O O O o oc 




Sand, ashes, 
cinders, organics, etc. 




Inclined 
conveyor 



Cardboard, rags, 
and textiles 



Paper 



Plastic bottles 
FIGURE 1. - Light-fraction upgrading process. 



Plastic film or 
plastic bottles 



Knife shredder 



Water 




Detergents and/or 
wetting agents 



Plastic and 
-*-i cellulose 



Conditioner 



Conditioner 




Vibrating screen 



Light metals 
(aluminum) 



Water and reagents 
(to be recycled) 



Cellulose 



Clear water Plastic 
(to be recycled) 



FIGURE 2. - Flowsheet for final cleaning of plastic film or bottles. 



Products emerging from the rough classification process described in 
references 1 and 2 can be utilized commercially. However, the market prices 
for such products are very low. On the other hand, the price may be increased 
by means of simple upgrading or finishing operations, which is justification 
for the needed research in this area. This is illustrated by the following 
process developments: 



70 



Feed 300 kg/hr 



(J^= 



Dry scrubber 





oooooooo 

OOOOOO 00 

ooooooo 

o ooooooo 

o ooooooo 


/ 



Inclined plane 




Cardboard, textiles, 
and massive iron 



Bypass 




Waste 



Dirt and labels 



>v Waste (to additional 
/ x treatment) 



DX Waste 

s/\ (to landfill) 



FIGURE 3. - Flowsheet for upgrading the ferrous product prior to detinning. 



1. Paper from plastic separation. 

2. Plastic upgrading. 

3. Upgrading magnetic scrap. 

The enormous quantities of food wastes, which may amount to as much as 
60 pet of the total refuse in Spain, support the need for research on the 
utilization of organic materials. This involves new research in the following 
specific areas: 

1. Energy production: 

a. Bioconversion (anaerobic biodegradation) . 

b. Solid refuse-derived fuel (RDF) production. 

2. Animal food production: Protein sources. 

Most of the work on utilization of organic materials is still in a preliminary 
stage. 

References 

1. Cavanna, M. , E. Riano, and J. Sanchez Almaraz. Installation and Results 

of the First Spanish Pilot Plant for the Treatment of Raw Refuse From 
Madrid (Spain) With U.S.B.M. Technology. Proc. 4th Miner. Waste Utiliza- 
tion Sump., cosponsored by the Bureau of Mines and IIT Research Institute, 
Chicago, 111., May 7-8, 1974, pp. 142-149. 

2. Cavanna, M. M., E. Riano, J. Sanchez Almaraz, and H. Garcia Ramirez. Latest 

Developments in Processing Spanish Urban Raw Refuse. Proc. 5th Miner. 
Waste Utilization Sump., cosponsored by the Bureau of Mines and IIT 
Research Institute, Chicago, 111., Apr. 13-14, 1976, pp. 141-145. 



71 



UTILIZING PROCESSED INCINERATOR RESIDUE AS COVER MATERIAL 
FOR SANITARY LANDFILL 

by 

R. E. Cummings 



The City of Philadelphia has for more than 50 years employed incineration in 
its solid waste management program to reduce the volume of waste materials prior to 
land disposal. In recent years, the incinerator program has involved two modern 
combustion facilities, employing the best available technology and fitted with 
electrostatic precipitators for air pollution control. 

Historically, the residuals resulting from these two facilities have been dis- 
posed of at land sites primarily within the City of Philadelphia. Continued use of 
sites within the city grows increasingly unlikely since such sites have all but 
disappeared. In addition, plans underway by the city envision at least one, if not 
more, energy recovery facilities utilizing solid waste as fuel. The end products 
of such combustion processes would be additional residue materials requiring land 
disposal. With diminishing acreages of disposal areas, it is clear that the energy 
plants of the future may be jeopardized by a lack of residue-disposal capacity. 

The residue quantity from the two incinerator facilities is approximately 
400 tons per day. At the city's Northwest Incinerator facility, residue from both 
plants was stockpiled for periods of up to one year prior to removal to land dis- 
posal sites. The residue was magnetically picked by a salvage operator under 
contract to the city to reclaim ferrous metal. It was felt that the combination 
of long-term storage and metal recovery altered the basic characteristics of this 
material — providing the opportunity for it to be considered as cover in sanitary 
landfill operations. 

In order to achieve the purpose of this program, the parties — 

1 . Placed 400 tons per day of incinerator residue in a suitable holding area 
at the Northwest Incinerator facility for a period of 6 to 8 weeks. 

2. Following suitable processing, removed this stored material from the hold- 
ing area at a rate up to 300 tons per day to the Montgomery County Sanitary Landfill 
Site. The movement of this residue material utilized city personnel and vehicles 
initially. Currently, a single contractor processes and hauls the material to 
Montgomery County. 

3. Utilized this material as daily and intermediate cover for the refuse 
disposed of in the Montgomery County Sanitary Landfill Site in a manner intended 
to duplicate as closely as possible the daily operating procedures currently 
employed at this disposal site. Some of the material was used for internal landfill 
roads and for testing as a final cover substitute. 

4. Monitored, tested, and evaluated the effects of the use of this residue as 
cover on the landfill operations, including observations of the residue as cover. 
Techniques were utilized that were designed to determine if the residue satisfies 
the physical requirements of suitability for cover, wrokability, prevention of 
rodents and other vectors, and containment of combustion within a cell. 

^he author is with Russell E. Cummings and Associates, Philadelphia, Pa. 



72 



The performance of the processed residue in its role as earth replacement for 
cover has been observed, monitored, and evaluated continuously since the inception 
of the shipments. Although more specific detailed evaluations are underway by 
Villanova University and the Department of Environmental Resources, the following 
observations can be made regarding criteria for suitable landfill cover: 

1. Workability. Landfill operating personnel verify independent observations 
that the processed residue has comparable workability to loose soil. It was spread- 
able and compactible, and covered the refuse adequately to meet State requirements. 
A particularly dramatic benefit of the material was its performance under wet 
weather conditions. According to Villanova, the residue did not soften when wet, 
owing to its granular, relatively cohesionless nature. This fact extended the 
landfill's operations under adverse conditions. 

2. Prevention of rodents and other vectors. No evidence of rodents or other 
vectors was observed as a result of the use of processed residue as soil cover 
replacement for the landfill . Additional monitoring of this fact is being conducted 
by county and State vector personnel . The material did not dry and crack so as 

to allow development of emergence of vectors . 

3. Containment of combustion in a cell. No fires have occurred during the 
demonstration period, and experienced observers foresee no increased chance of 
uncontrolled fire based on this material as compared to soil. 

4. Control of blowing paper. The processed residue performed the same role 
as normal earth cover in preventing the emergence of paper and litter through the 
cover. Had the material settled through the refuse due to an overly granular 
nature, problems of blowing paper would have occurred. 

5. Suitability for revegetation. To evaluate the revegetative capabilities 
of the processed residue, a special testing program was established at the landfill 
and in the greenhouse at the consultant's labs. The primary purpose of the first 
tests was focused on the ability of the material to support and maintain grass 
growth. The processed residue combined with sewage sludge produced 3 to 5 inches 
of grass in thick quantities within 2 months . This growth reemerged in March and 
April 1978. 

For a landfill that must use imported over, such as the one operated by 
Montgomery County, the possibility of cost savings can become reality. For 
example, the county pays $1.65 per cubic yard for its cover. At the projected 
rate of 300 tons per day, the value of the processed material can be as much as 
$155,000 per year. At the average rate of refuse receipts at the landfill, this 
would be equivalent to approximately $1 per ton. 

The City of Philadelphia benefits by eliminating the haul of the material to 
current New Jersey landfills. The mileage saved is about 30 miles. Even if the 
haul were the same to an alternate landfill, the city could project a value equal 
to the price of disposal in comparable Pennsylvania landfills. For example, based 
on the Montgomery County disposal price of $7 per ton, the processed material turns 
a $650,000 liability into an equally valuable asset. 



73 



SOLID WASTE CHARACTERIZATION FOR RESOURCE RECOVERY DESIGN 

by 
J. P. Woodyard 1 and A. J. Klee 2 



Solid waste characterization, as defined here, refers to the estimation 
of the quantity and composition of solid waste available to a resource recov- 
ery system. Because exact information cannot be obtained, an acceptable level 
of estimate accuracy must first be identified in order to define the scope of 
the waste survey. Investors, designers, and markets may all specify an accu- 
racy requirement; it is then left to the survey planners to decide how that 
level of accuracy can best be obtained. 

Accuracy versus Precision . — The terms "accuracy" and "precision" are 
often used interchangeably but have entirely different meanings when describ-' 
ing a waste quantity or composition estimate. Accuracy refers to the close- 
ness of an estimated value to the true value of the parameter being measured; 
precision refers to the repeatability of the measurements. To illustrate the 
subtle but important difference, imagine that an engineer is responsible for 
estimating the daily waste generation rate in City X. A review of the litera- 
ture results in 10 per capita waste generation estimates that are close to one 
another in magnitude. Concurrently, random selection of 10 collection routes 
with known daily waste loading and population results in 10 widely scattered 
per capita estimates. The 10 literature estimates provide a more precise 
estimate of waste generation, while the 10 field measurements will likely 
provide a more accurate estimate of the true waste generation rate (assuming 
the route selection was truly random) . In fact, only a well-designed field 
survey can provide an a priori estimate of the expected accuracy of the 
results. 

Precision (and accuracy) is expressed as a percentage interval about the 
estimated mean (for example, ±10 pet) . Because the size of the interval will 
be a function of sample number, accuracy requirements will actually dictate 
the level of effort necessary to properly perform the survey. This require- 
ment is usually comprised, if not totally neglected, when the waste character- 
ization budget is insufficient. As a result, past practice in waste character- 
ization would not be expected to reflect the actual needs of resource recovery 
planners . 

Waste Characterization Accuracy Requirements . — To determine the waste 
characterization accuracy required by the resource recovery community, quanti- 
tative accuracy requirements were solicited from designers and secondary mate- 
rial buyers. The sensitivity of system economics to inaccurate waste charac- 
terization was assessed through computer simulation. 

•^Project manager, SCS Engineers, Long Beach, Calif. 

2 Chief, Processing Branch, U.S. Environmental Protection Agency, Cincinnati, 
Ohio. 



74 



Design Requirements . — Design accuracy requirements are specific to each 
unit operation in solid waste processing (that is, receiving and storage, 
handling, shredding, classification, screening, magnetic separation, and 
thermal processing) . These requirements were provided by the E-38 Committee 
of the American Society for Testing and Materials (ASTM) and are summarized 
in table 1. Supplemental data on design accuracy requirements were also 
obtained from (1) size-reduction equipment designers and operators, (2) incin- 
erator operators, and (3) consultants experienced in resource recovery design, 



TABLE 1. - Waste characterization accuracy requirements 



Unit operation 


Precision, pctl 


Parameters 


Quantity estimation: 


±10-20 
±10-20 
±10-20 
±10 
±10-20 
±20-50 
±10-20 


Tons per day. 

Tons per unit time. 

Do. 

Do . 




Do. 
Do. 
Do. 




Critical waste 
components 


Design sensitivity 


Composition estimation: 


OBW 


Low. 


All 

Glass, garbage. 


Medium . 
Do . 




Do . 


Magnetic separation 


Medium — low. 
Medium . 




Medium — high . 



Demo Demolition waste. OBW 
Represents mode of responses 
±100 pet. 



Oversized bulky waste. 
; range in most cases was up to 



The findings indicate that both quantity and composition accuracy 
requirements for resource recovery design vary with each unit operation. 
ASTM reported accuracy requirements for quantity estimation that were as 
stringent as ±10 pet. Requirements for composition estimation appeared less 
critical and were based on the identification of specific components in the 
waste stream. Each unit operation tended to be sensitive to one or more com- 
ponents. Less stringent design accuracy requirements were reported by proc- 
essing designers, manufacturers, facility operators, and consultants. These 
requirements were generally based on the literature and incorporated some 
degree of conservative design. 



The diversity of responses indicates that design accuracy requirements 
have been specific to each designer. No industry standards exists. The ±10 
to 20 pet precision figure was subsequently used as a target specification 
for developing the statistical survey design but should be interpreted only 
as a worst case specification for experimental work. 



75 



Marketing Requirements . — Accuracy requirements are an important consider- 
ation in the marketing of materials and energy recovered from solid waste. 
High-technology systems may generate more material than low-technology systems 
in the same waste shed. To develop the stable market conditions necessary for 
this larger amount of material, investors require long-term contracts for the 
sale of recovered materials. Before signing such contracts, buyers will often 
require that the quantity and quality of material to be sold be specified with 
a certain degree of accuracy. Price is sometimes determined based on expected 
volume, and penalties for inaccurate estimation have been incorporated in some 
contracts . 

Reporting of Results . — The reporting format and level of detail desired 
may be specified by the ultimate uses of the survey data. If not, the results 
should be reported in summary form with a brief review of the procedure used 
(assumptions, data sources, etc.). The following general guidelines of what 
not to report are also offered: 

1. Do not report quantity or composition data by route or hauler, if 
possible, as many haulers feel this information is confidential. 

2. Do not report the results of the survey without some description of 
the survey procedure used. Others may use the data later and should know its 
limitations . 

3. Do not report the data without the computed confidence intervals; 
interpretation of the estimate should be left to the user of these estimates. 

4. When using published data in place of part or all of the survey, 
reference it as such and do not publish it again as "local" data. This only 
serves to perpetuate data that may be outdated or of questionable origin. 

The characterization of solid waste is typically a low-priority item in 
resource recovery design. Designers and markets are beginning to develop 
more stringent accuracy requirements, thereby necessitating the use of field 
surveys to satisfy these requirements. Through statistical design, these 
surveys can be performed for a reasonable cost. Field surveys should be more 
widely used in place of published estimates. 



76 



MARYLAND ENVIRONMENTAL SERVICE-BALTIMORE COUNTY 
RESOURCE RECOVERY FACILITY, TEXAS, MD. 

by 

C. R. Willey 1 and M. Bass in 2 



In 1970, the State of Maryland created an agency, the Maryland Environ- 
mental Service (MES), one of the first of its kind in the Nation, to provide 
planning and utility services for sewage, water supply, and solid waste man- 
agement to counties, municipalities, and industry. MES now operates 56 
sewage treatment plants, a 60-ton-per-day compost plant which converts sludge 
to solid compost for agricultural use, a 100-ton-per-day sludge dehydration 
project, and a sludge trenching project averaging 270 tons per day and over- 
sees the operation of the Baltimore County Resource Recovery Facility. 
Included in MES' plans for the future are a 240-ton-per-day sludge recycling 
plant, operation of additional sewage and water treatment plants, and other 
resource and energy recovery systems for municipal solid wastes. 

In 1972, MES began investigating possible designs for a Maryland reclama- 
tion project. Concurrently, Baltimore County initiated studies to identify 
alternate disposal methods and/or locations for a refuse disposal facility in 
the county. The limited life of the Texas Sanitary Landfill near Cockeysville. 
Md., dictated that other means for northern Baltimore County solid waste dis- 
posal would have to be provided. Accordingly, MES and Baltimore County 
entered into a joint venture to create a resource recovery facility to serve 
the northern county. 

Teledyne National was selected as prime contractor and system integrator 
for the associated marketing, facility design, construction supervision, and 
operation. A parcel of land was selected at the Texas Sanitary Landfill and 
in August 1974 site preparation was begun. 

In this paper, an overview of the project will be presented with emphasis 
upon unique features, especially associated market and product development. 
To maintain proper perspective, the separation and recovery processes and 
equipment will also be described. 

The MES-Baltimore County Resource Recovery Facility (fig. 1) designed to 
process up to 1,500 tons per day, started operations in January 1976. Early 
on, four separate stages were planned: 

1. A transfer and shredding facility with ferrous metals being recovered 
and sold. 

2. A system for producing refuse-derived fuel (RDF) and selling it. 



Chief, technical services, Maryland Environmental Service, Annapolis, Md. 
2 Director, product planning, Teledyne National, Northridge, Calif. 



77 



3. Full-scale tests and demonstrations for recovery of glass and non- 
ferrous metals. 

4. Full-scale operations. 

The system for resource recovery features dry separation and recovery in 
a basically modular, redundant design to provide maximum reliability and flex- 
ibility in terms of growth and technological advancements. An average of 
about 400 to 500 tons per day of municipal solid waste (MSW) has been received 
and processed at the resource recovery facility since the start of operations. 
When the new southwest Baltimore County transfer station goes onstream in the 
spring of 1978, the quantity of MSW delivered to the facility is expected to 
double . 

Trucks enter the resource recovery facility in a one-way pattern and 
proceed to an automated weigh station and then to the staging and unloading 
areas . 




1 . AUTOMATED WEIGH STATION 

2. STAGING AREA 

3. OVERFLOW PIT 

4. SHREDDER INPUT SYSTEM 

5. SHREDDER 

6. SHREDDER OUTPUT SYSTEMS 



7. FERROUS SEPARATION 

8. LOADING TOWER 

9. FUEL PROCESSING INPUT SYSTEM 

10. FUEL PROCESSING AREA 

11. SECONDARY SEPARATION AND 
RECOVERY AREA 

12. PRODUCT MANUFACTURE - 
FUTURE 



FIGURE 1. - Schematic flow chart of Maryland Environmental Service-Baltimore County 
resource recovery facility. 



78 



The ME S/ Baltimore County Resource Recovery Project, employing relatively 
low-risk dry separation and recovery processes and equipment, will provide 
light fraction for sales as RDF, for sludge treatment, or for building mate- 
rials depending upon changes in refuse composition, existing markets, and the 
associated economics. 

The RDF burn program in the boiler of a large paper company has been com- 
pleted. The paper company is now considering the use of RDF for its future 
energy requirements. RDF tests in a lightweight aggregate kiln were success- 
ful at conservative Btu replacement ratios of 70 pet RDF to 30 pet coal. 

A burn program with the participation of the EPA is scheduled this year 
in a cement kiln. 

Additional light fraction will be supplied for composting with sewage 
sludge at the U.S. Agricultural Research Station in Beltsville, Md. 

Glass products, specifically GPC pipe, foamed glass insulation, and 
lightweight aggregate, have been developed to production readiness. 

Ferrous is being sold to a steel manufacturer; a contract for the sale 
of aluminum will be finalized this year. Several companies have expressed 
an interest in recovered mixed nonferrous. 

The impact of additional MSW from the new transfer station on economy 
of scale, the continued development of RDF markets, and the sale of aluminum 
will provide the basis for economic evaluation of this project. 



79 



IMPACT—PAPER RECYCLING VERSUS SUPPLEMENTAL FUEL 

by 
H. J. Perry 1 



Although at present there are only a few scattered energy plants that use 
municipal solid waste as a supplementary fuel, it appears that the trend is 
upward as landfill sites become increasingly scarce. Certainly this use of 
trash is ecologically sound. However, there are increasing signs of concern 
over the possible loss of waste paper from the historical recycling pattern 
into paperboard, construction paper, and the board industry. In addition, 
the relatively new industry of recycling old newspapers back into newsprint 
can be affected because it is largely dependent upon the metropolitan areas 
for its raw material and these areas are the most likely to use trash for 
supplemental fuel. 

Numerous studies indicate that the United States may be faced with a wood 
shortage anywhere from 1990 to 2025. Certainly, it is becoming more difficult 
to increase the wood supply in view of future legislation, court decisions, 
emotions, and environmental concerns, real or imagined. Thus, it seems wise 
at this time to consider the effects of burning of cellulose fiber and build- 
ing long-life systems for its destruction as fiber. 

While it is uncertain at this time to project the increasing demand for 
waste paper very far into the future because of the complicated economic 
problems of reuse, now is the time to give the problems considerable thought. 

We seem to be faced with two major questions. Do we restrict the collec- 
tion of waste paper in our municipalities for recycling back into the paper- 
board industry or reserve it for steam generation, or do we use steam genera- 
tion as a secondary system to consume waste paper where the supply exceeds the 
demand? 

In the first case, this situation has occurred in the Saugus, Mass., area 
wherein all municipal solid waste is reserved by municipal ordinances for 
steam generation. This action has upset the local sources of supply of old 
newspapers and old corrugated cartons normally used by the local board mills . 
It appears to have had serious economic consequences. In the second case, it 
is the normal historical pattern of disposal or recycling. As waste paper 
exceeds demand, more is landfilled or incinerated. 

Thus, we come to another important question — how much effect does 
increased consumption of waste paper have on the calorific value of municipal 
solid waste? There is little change in Btu values under the various assumed 
conditions under study. On the dry basis, 8,000 Btu per pound seems to be a 
fair value. On the wet basis, 24.5 pet moisture, which is the basis of feed- 
ing the steam generators, the fair heat value is 6,000 Btu. No consideration 

^-Professional engineer, Henry J. Perry Associates, Williamsville, N.Y. 



80 



has been given to some noncombustible carryover in a shredding and air classi- 
fication. The ash content is likely to vary in the various components. So, 
5,000 Btu as used in many estimates is a conservative value. 

A potential decline of waste paper in municipal solid waste has several 
environmental consequences — less collected tonnage by municipal authorities 
and more concentration of noncombustibles at a processing plant. It seems to 
justify separation operations because of sizable volume of glass and metals. 
If cullet can be sorted by color as research indicates, a market can be devel- 
oped for glass. Therefore, so far as the facts are known, the collection of 
waste paper for recycling will not change the supplemental fuel heat value. 
It is, therefore, unnecessary for municipal authorities to impose restrictions 
on the collection of waste paper for recycling unless the decline in volume 
makes steam generation unwarranted, a condition that seems unlikely. Lowering 
the volume of waste paper by various collection systems will actually be 
beneficial by lowering trash collection costs for municipalities. 

As important as reduction in collection of trash is to a municipality in 
reducing costs, a major reduction by salvage at the curb level could reduce 
the quantity to the point where it could affect the profitability of a plant 
designed to use trash as a primary fuel. It would seem wise therefore to 
consider trash as a secondary fuel because it is unlikely that minimum quan- 
tities of trash would balance with minimum steam or energy demands . 



81 



NEW RECLAIMING PROCESS FOR WASTE PAPERS 

by 
K. Saitoh, 1 N. Mishijima, 1 and A. Kimura 1 



At present Japanese paper production amounts to 15.4 million tons per year, and 
6.3 million tons of them are recovered and recycled as waste paper. The 38 pet 
reclaiming rate (1) is twice as high as that of the United States and will probably 
increase to 50 pet in the near future owing to a lack of timber resources. 

From the standpoint of material and energy savings, recently there have been 
strong demands for the development of new processing techniques for waste papers. 
Conventional reclaiming processes for waste papers have many problems; for example, 
too high consumptions of water and electricity, clarification of waste water, dis- 
posal of sludge produced from the thickener, and high operation costs. Research was 
conducted on the processing of printed waste papers which contain large quantities 
of ink and clay. As a result, a new reclaiming process was developed. 

The process itself has a number of advantages and has been greatly simplified 
and improved. It also yields great savings in terms of overall operating costs. 
Patent applications for this new system have been made in Japan and abroad. Printed 
waste papers are processed in the following steps: Disintegration, ink flotation, 
fiber recovery from deinked pulp, and clay flotation in waste water. 

In disintegration, waste papers are fed into a hydropulper where they are pulp- 
ified and contaminants are removed from the paper fiber by using alkali and sodium 
silicate to promote def iberization. The disintegrated pulp is fed into an ink flo- 
tation cell where small air bubbles are generated uniformly from the cell bottom 
where air is blown into specially equipped porous bodies. Ink flotation is promoted 
by adding surface-active agents, such as petroleum group agents, oleic acid, and 
pine oil. In the next step, fibers are recovered as oversize from the deinked pulp 
by using a vibrating screen. White waste water through the screen containing large 
amounts of fine clay is supplied to a clay flotation tower. Then the floes readily 
float, adhering to the air bubbles. The vertical flotation cell is also available 
for clay flotation. Recovered clay containing high-quality kaolinite can be sup- 
plied as refractory materials and as various fillers after calcination. Since the 
clay flotation efficiency is very high and the effluent from the process is very 
clean, it is possible not only to discharge the effluent but also to reuse it again. 

Although the reclaiming rate of waste paper in Japan is increasing yearly, the 
effluent and sludge discharged from reclaiming plants are being regulated continu- 
ously in terms of pollution control. Consequently, reclaiming plants for waste 
paper have to have not only low operation, but also a clean system free of harmful 
discharges . 

The new reclaiming system features a unique process with equipment specially 
designed to meet the current demands . As the world supply of natural resources 
diminishes, the need for reclaiming and utilizing waste papers becomes more and more 
urgent . 

Reference 

1. Hiraoka, M. Utilization of Waste Paper and Its Technical Problems. Japanese 
Tech. Assoc, of Pulp and Paper Industry, August 1977, pp. 39-47. 

!A11 of the authors are with the Central Research Laboratory, Mitsui Mining & 
Smelting Co., Ltd., Tokyo, Japan. 



82 



INDUSTRIAL WASTES 
RECYCLING SCRAP—A DECADE OF CHALLENGES AND FRUSTRATIONS 

by 

H. Ness 1 



We all know that recycling conserves material resources, reduces solid 
waste disposal, and conserves energy. At the beginning of this decade, there 
seemed to be some doubt of how effective recycling really is. Therefore, dif- 
ferent Government agencies prepared extensive reports and surveys to gage its 
impact and effectiveness. Now, after 10 years of official scrutinizing and 
analysis, we know much more about recycling's values and potentials. We can 
pinpoint how much energy can be saved, we can pinpoint the conservation of 
natural resources, and we can pinpoint how much we can reduce the size of our 
growing solid waste load. 

That is what we have been able to accomplish in these last 10 years. 
Unfortunately, however, none of this has actually resulted in measurable 
increase in the recycling of metallics and other materials. To the contrary, 
all of the favorable surveys aside, recycling is very much what it was a 
decade ago. We have come far in understanding the need for recycling but not 
in accelerating recycling in any measurable degree. 

On figures 1-6 the recycled commodities are plotted versus their virgin 
counterparts for the period from 1968 to 1977. Looking at each commodity, we 
can get a picture of what has happened in the last decade. 

Aluminum . — Secondary aluminum shows a slight but steady increase for this 
period. Primary production of aluminum except for 1975 shows a more rapid 
rate of increase than secondary. With the amount of publicity and effort that 
has gone into recycling of aluminum during this period, one would expect a 
better performance of secondary than is indicated here. 

Copper . — The spread between "purchased copper scrap" and "refined copper" 
increased during most of this period. It is readily apparent by looking at 
figure 2 that recycled copper lost ground almost every year. 

Iron and Steel .— Purchased iron and steel scrap follows almost the iden- 
tical path that steel production takes, only on a lesser scale. Here, too, 
one would have expected — because of the publicity and exposure — scrap to 
increase at a greater rate. 

Lead . — Secondary lead is the only commodity of those considered here that 
gains a little each year as compared with its virgin counterpart. Battery 



technical director, National Association of Recycling Industries, Inc., 
New York, N.Y. 



83 



6000 - 



5000 



c 
o 
c 
to 4000 



w 




3000 



2000 



1000 



Primary Production 
of Aluminum 



Secondary Recovery of Aluminum 



J_ 



X 



X 



X 



X 



X 



J 



1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 

FIGURE 1. - Aluminum. (Courtesy U.S. 
Bureau of Mines.) 



2400 _ 



2200 _ 



H 2000 _ 



'H 1800 



1600 



1400 _ 



1200 _ 



1000 




1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 

FIGURE 2. - Copper. (Courtesy U.S. 
Bureau of Mines.) 



160 [- 




1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 

FIGURE 3. - Iron and steel. 




400 



1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 



FIGURE 4. - Lead. (Courtesy U.S. Bureau 
of Mines.) 



1500 - 




FIGURE 5. - Zinc. (Courtesy U.S. Bureau 
of Mines.) 



60000 - 



50000 



CO 40000 



30000 



20000 




Production of 
Paper & Board 



- Paper Stock Consumption 



10000 



X 



X 



X 



X 



X 



X 



X 



X 



J 

1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 



FIGURE 6. - Paper. (Courtesy U.S. Depart- 
ment of Commerce, Bureau of 
Domestic Commerce.) 



84 



recovery accounts for the greatest part of secondary lead recovered. The fact 
that usually one returns a used battery when purchasing a new one helps keep 
the amount of secondary lead recovered high. 

Zinc . — The amount of zinc scrap recovered in comparison with zinc consump- 
tion is low to begin with, and through the years, continues to decrease. The 
recovery of zinc scrap does not keep pace with zinc slab consumption. Of 
course, one of the reasons that recovery is so small is that zinc is used in 
and on products as coatings and pigments, and these are not easily recoverable, 
However, this does not explain why zinc scrap does not keep up with zinc 
consumption. 

Paper . — To most environmentalists — and to many in the industry — paper 
stock consumption has been one of the biggest disappointments in all the 
recycled commodities. Paper stock consumption has not kept pace with the 
production of paper and board. In addition, the rate of recovery is still 
very low, approximately 20 pet. We know that this rate can be increased sub- 
stantially. During World War II, U.S. recovery rates rose to over 35 pet. 
Other countries' paper recovery rates have gone up to 50 pet. 

Certainly, the prime indicator of how we are doing in recycling of any 
particular commodity is the recycling share of the market. In point of fact, 

this indicator is the ratio of amount of recycled material recovered or used 
to the total amount of the material produced or consumed. 

The recycling share of the market for each of the materials discussed is 
shown in table 1 for 1968 and 1977. Aluminum shows an increase, but of only 
1 pet for the entire decade. Lead is up from 42 pet to 47 pet. All of the 
remainder are either the same (iron and steel) or down (copper, zinc, and 
paper) . 



TABLE 



!• ~ Recycling share of market, pet 



Aluminum 

Copper , 

Iron and steel 

Lead 

Zinc , 

Paper 



These figures and charts represent a frustrating and disappointing story 
the" L\Tio" n years Y ^ "" 1±ttU Ch " 8e in the tm '"A* ^* *°* 

Recycling will occur only when economic conditions justify it. In recy- 
cling, as in any other major industry in America, the profit motive is a prime 
factor Supply and demand must be balanced. If there is an oversupply of 
material demand retracts and prices spiral downward, reducing the incentive 
on an industrywide base to collect and process recoverable material 



85 



Why isn't more material recycled? What must be done to enable recycling 
to expand — to move material from the solid waste pile to the resource supply? 
Where are the present bottlenecks? In order to expand recycling, the most 
critical need is markets. Our direction sign reads: Markets first, collec- 
tions second. 

In order that the recycling industry may work to its maximum potential in 
helping to solve the urgent problems of energy and resource conservation and 
solid waste disposal, the industry must have — 

1. Expanded research, with emphasis on developing means of utilizing 
lower grade solid waste, including unsegregated materials and mixed refuse. 

2 . The development of new equipment and new techniques capable of 
processing recycled materials on a more economic basis. 

3. Changes in tax policies to encourage and stimulate recycling, similar 
to those now accorded most other major industries. 

4. Freight rates that are nondiscriminating, fair, and reasonable. 
These rates on recyclables are often double those placed on competing 
commodities . 

5. The need for programs to create expanded markets for products con- 
taining recycled materials, with emphasis on eradicating discriminatory pur- 
chasing policies and irrational specifications. 

6. The need for changes in onerous zoning, licensing, and other local 
operating regulations, which now inhibit the growth of the recycling industry. 

7. The education of consumers — the purchasing public — as to the quality 
of products made with recycled materials and the intrinsic environmental 
values of purchasing such products. 

These represent effective responses to some of the basic bottlenecks to 
recycling and the reasons why present available metals may go to the dumps 
instead of being utilized. These are all vital steps in helping to make 
recycling a truly viable force in our economic system. 

Of the seven items listed, the first two — expanding research and develop- 
ing new technology and equipment to economically recycle material — should be 
considered the major challenges. 

Economical technology has to be researched and developed for new methods 
of taking low-grade metallic wastes and recovering the metal contents. It is 
only when the material that now goes to the dumps is economically salvaged 
that we will be able to show increased national recycling rates that will be 
truly meaningful. 



86 



WASTE MANAGEMENT STRATEGY FOR MAJOR INDUSTRIES 

by 
J. J. Emery 1 and D. B. Matchett 1 



Industrial waste management has acquired urgent significance because 
environmental pressures and regulations are growing at the very time when the 
necessary profitability to incur capital investments for combating pollution 
is being squeezed by increasing energy, raw materials, and labor costs. The 
control of gaseous and liquid emissions, solid waste handling and disposal, 
and special problems such as noise, vibration, heat pollution, and radiation 
all call for increasingly sophisticated and expensive equipment, often requir- 
ing more company resources than the actual production process involved (3) . 
When it is considered that an estimated 270 million metric tons of industrial 
wastes are generated annually in the United States, with 10 pet classified as 
hazardous by the Environmental Protection Agency, the magnitude of the problem 
becomes clearer (2_) . Pollution control is big business, as reflected by the 
approximate $11 billion to be spent in the United States for control of air, 
water, and solid waste pollution during 1978; that is, almost 7 pet of all 
planned capital spending by business. The situation is similar in Canada for 
major industries. 

The interrelationship between energy and pollution is being increasingly 
recognized, given the escalating cost of energy since 1973. Significant 
energy has often been invested in waste and byproducts during primary product 
production that is lost when simple disposal replaces recycling, recovery, or 
utilization. Waste should obviously be minimized at all stages of production, 
and any wastes produced should be recycled where possible to both conserve 
raw materials and reduce energy consumption (1) . Energy accounting during 
waste management, while a simple concept, requires much more attention as part 
of an overall waste management strategy. 

While the environment and energy have been important factors focusing 
attention on waste management, the problem of waste disposal is probably the 
critical factor for many industries. For plants in urban areas, the total 
cost of disposal (collecting, handling, transportation, dumping) to approved 
sites ranges from about $5 to $15 per metric ton. Further, municipal authori- 
ties are tending to limit the dumping of industrial wastes in landfill sites 
(that is, reserving capacity for domestic refuse) and are requiring major 
plants to develop their own disposal areas that must meet increasingly strin- 
gent environmental controls. Liquid and hazardous wastes require a much 
higher investment in acceptable disposal methods and sites, and a number of 
companies have entered this market to provide the necessary services, often 
at a substantial unit cost to meet a wide range of governmental regulations. 
A major activity is the solidification of sludges and liquid wastes by a 
number of proprietary processes. 

Both authors are with the Department of Civil Engineering Mechanics, Construc- 
tion Materials Laboratory, McMaster University, Hamilton, Ontario, Canada. 



87 



Implicit in the above discussion of general waste management concepts is 
the question of how the necessary capital will be generated to combat indus- 
trial pollution and improve the environment . While it is clear that the pub- 
lic will not tolerate a decline in the environmental standards already 
attained, it is also clear that any reduction in standards of living through 
restricted plant operations, decreased growth, or even closure to meet these 
standards will not be popular. In general, the capital must come from the 
industry, with increased governmental support to combat pollution whenever 
required, and recognizing current financial constraints. It is considered 
that an integrated waste management strategy plays a key role here, as it 
can reduce both disposal costs and environmental pressures while contribut- 
ing to the overall profitability essential for financing further pollution 
abatement. A waste management group with a well-developed strategy should 
form an element of corporate structure to focus on the problems and costs of 
waste disposal and to take advantage of potential savings. 

Since the waste management strategy described here was developed as part 
of waste and byproduct utilization studies in the Construction Materials 
Laboratory, and by the Trow Group Limited Consulting Engineers, for the 
foundry, iron and steel, nonferrous, and cement industries, the emphasis is 
on solid wastes with general background information drawn from the iron and 
steel sector. However, the importance of including liquid and geseous emis- 
sions in the strategy is recognized, and some general concepts of energy 
accounting and waste are introduced here. 

The key elements of the waste management strategy that have evolved are — 

1. Determining the types, characteristics, and quantities of wastes and 
byproducts for each major process and/or product, including energy accounting. 
This should include both present and future waste generation, typically in 
terms of waste generation coefficients (waste per unit of product) . Simple 
materials (and energy) balances for processes will often yield much improved 
estimates of waste quantities and the disposal problems involved. 

2. Reducing the loss and/or degrading of materials and energy during 
processes. This aspect of a waste management strategy is described in the 
next section. 

3. Encouraging recycling and/or recovery of wastes and byproducts where 
feasible in the plant, or in other industries that can use the byproduct. 

4. Optimization of waste collection, handling, transportation, and dis- 
posal systems. This will require close cooperation of the production, utili- 
ties, transportation, and planning staffs involved. 

5. Development of potential applications for wastes and byproducts. 
Must include a marketing strategy that reflects the technical and economic 
constraints involved. This is the subject of a companion paper and will not 
be covered here except to emphasize the importance of taking advantage of a 
waste's inherent energy and materials value in applications involving recover- 
able and replaceable energy, or special materials features. Waste materials 
exchanges offer a valuable method of making the necessary contacts. 



88 

6. Design of waste disposal sites and storage areas for materials that 
may have future recyclability or uses. Must be in terms of immediate and long- 
term regulations. While not a direct step, overall coordination and review of 
the waste management strategy by a waste management group with active senior 
level participation is required to ensure that the interacting objectives are 
met within the rather complex organizational framework of major industries. 
The major difficulty often appears to be the initial step — implementation — 
with the resulting savings providing the necessary impetus for further steps. 

Although the framework for a suggested waste management strategy has been 
given, it is clear that each company must develop an individual strategy meet- 
ing its specific requirements. However, it is considered that a common 
feature throughout will be a recognition of the importance and interaction of 
pollution and energy. Based on the writers' experience in the Hamilton area, 
it is clear that a waste management strategy can make a positive contribution 
to company profitability and should form an aspect of overall corporate 
planning . 

References 

1. Barnes, R. S. Steelmaking and Its Future. Endeavour, New Series, v. 2, 

No. 1, 1978, pp. 1-6. 

2. Engineering News-Record. EPA Set To Clamp Down on Toxic Waste Disposal. 

Mar. 16, 1978, p. 13. 

3. Heynike, J. J. C. Some Aspects of Energy and the Environment in the Steel 

Industry. J. S. African Inst. Min. and Met., September 1977, p. 24. 



89 



IRON AND CARBON RECOVERY VIA THE RECLAFORM PROCESS 

by 
J . S . Young , Jr . * 



The utilization of the Reclaform Process is indicated whenever a fines 
management situation arises where additional carbon units are desirable or at 
least innocuous. The carbonaceous binder system results in 80 to 90 pet of 
the initial binder weight reporting as carbon in the final agglomerate. Areas 
of application that have been evaluated or are underway include iron and steel 
fines management, foundry fuel, carbon silica composites for hot blast cupolas, 
dezincing and metallization or smelting of steelmaking fines, flux-metal fines 
composites, industrial charcoal agglomerates, and charge agglomerates for lime 
regeneration kilns . 

With emphasis on carbon, projects dealing with furnace coke, foundry coke, 
and petroleum coke are aimed at better understanding of surface area, stabil- 
ity, reactivity, porosity, and chemistry effects. Efficient utilization of 
energy and carbon resources is the primary goal of this work. 

A roll briquetter forms the Reclaform briquet at relatively low pressure 
without further fracturing of the particles being recovered. The binder sur- 
rounds these particles and is polymerized, resulting in a matrix rich in 
carbon-carbon bonds, which imparts the necessary strength for materials 
handling and furnace consumption. Since this binder system relies very little 
on the bound particles for its strength, it can be applied to a wide range of 
particulates . 

Figure 1 outlines the Reclaform Process . Sized raw materials are blended 
and dried or preheated. Hot binder is injected into the mixture with close 
temperature control and mixed prior to feeding the roll briquetter. The green 
briquets are screened and fed to the curing oven, where precise temperature 
and air flows are controlled to polymerize the binder and result in a cured 
carbon matrix. Zoned curing temperatures range from 450° F (232° C) to 
600° F (316° C) . In curing, a controlled exothermic reaction occurs which 
signals polymerization. Time, temperature, gas flow, gas composition, 
briquet permeability, and the binder used are all important factors in the 
design and operation of the curing oven. Condensable hydrocarbons released 
during curing are incinerated with the heat recovered and used in the drying 
stage and the oven itself. After curing, briquets are discharged and ready 
for immediate consumption or storage as mill operations require. Storage 
presents no problem since the briquets do not require special handling or 
protection from the weather. 



technical manager, Reclasource Corp., Chicago, 111. 



90 



RAW 


— 














MATERIAL 






BLENDING 




















i — 


-— 


AIR POLLUTION 
CONTROL 


FEEDSTOCK 






DRYING 


















i 

HEAT 
RECOVERY 


BINDER 
FEED 




BINDER 
MIXING 
















1 
I 

• 




BRIQUETTING 




INCINERATION 










1 

1 

1 




CURING 














WEIGHING 














STORAGE 




FIGURE 1.- F 
f 


"low d 
orm pr 


iagrarr 
ocess. 


of the Recla- 



A 10-ton-per-hour pilot plant was 
constructed and commissioned by Recla- 
source for the recovery of coke breeze, 
mill scale, blast furnace dust, blast 
furnace sludge, and basic oxygen furnace 
dust at the site of Crucible Alloy Divi- 
sion, Midland, Pa. The plant was field- 
engineered using for the most part 
available, known equipment. The major 
exception was the installation of an 
experimental curing oven which has pro- 
vided information for the design of a 
full scale production oven. Figure 2 
is the pilot plant layout diagram. 




( 



RAW MATERIAL 
STORAGE 



t- < 

< X 

5° 



FEED HOPPER ITYP) 



n 



ORE 



MAINTENANCE 
STORAGE 




MCC 


CONTHOi 

ROOM 


OfflCt 


LAD 



BRIDGE 



FUEL OIL STORAGE 
(**• 4 PUMP PIT 



INCINERATOR ' 



□ 



-a 



So 

i- < 

< cc 

1° 

< 



LIMIT 



CONVEYOR (TYP.) 



I 

BRIOUETTER I 

I 



-n- 



M 



BAGHOUSE 



MIXER I 1 



BINDER STORAGE 
& PUMP PIT 



FIGURE 2. - Typical Reclaform plant layout. 



91 



RECOVERY OF ZINC OXIDE FROM GALVANIZING WASTES 

by 

J. B. Stephenson, 1 P. G. Barnard, 2 
and A. A. Cochran 3 



Importing approximately 50 pet of the zinc consumed in the United States 
has underscored the need to recover the metal from brass and bronze flue 
dusts, steel furnace dust, diecastings, sludges, and galvanizing wastes (4-7). 
The Bureau's Rolla Metallurgy Research Center has been investigating the 
recovery of zinc from a variety of wastes including those from galvanizing. 
Previous Bureau research resulted in a process for the recovery and reuse of 
sal skimmings for flux solutions (8) . Dross can be treated in special liquid- 
ation furnaces to lower its iron content, or distilled to produce zinc dust 
or slab zinc (2) . Zinc recovery from galvanizing ashes is difficult because 
the material is a complex mixture of oxides, metallic zinc, and chlorides. 

Galvanizing wastes are zinc-bearing secondary domestic resources made 
up of dross, ashes, and sal skimming (1, 3). Zinc dross, a mixture of zinc- 
iron alloys, forms in galvanizing kettles or furnaces through the interaction 
of hot zinc with steel or iron. Sal skimmings are spent fluxes from cleaning 
steel prior to dipping in the molten zinc, and zinc ashes are the zinc oxide 
that forms at the molten zinc surface in the galvanizing kettle. Hot-dip 
galvanizing, with about 25 pet of the total galvanizing market, has average 
zinc losses of 22 pet dross, 12 pet flux, and 17 pet ashes. From other types 
of galvanizing, such as strip and sheet, the production of dross and skimmings 
ranges from 5 to 10 pet. The combined total of these zinc losses amounts to 
80,000 to 120,000 tons per year (9). The recent closing of zinc smelters 
using the horizontal retort process greatly decreased the market for this 
type of zinc-bearing waste. 

A chlorination process for galvanizing ashes, of immediate interest to 
industry, was developed on a laboratory scale. Lead levels of 0.25 pet could 
not be attained at 900° C with CaCl 2 as the chlorination agent. Chlorinating 
the galvanizing ashes with 2.5 pet CaCl2 and 1 pet Si0 2 at 900° C for 1 hour 
consistently produced a zinc oxide product containing less than 0.25 pet lead 
that was suitable for metallurgical and chemical use. The zinc oxide product 
contained over 90 pet of the zinc present in the roasting feed; less than 
10 pet of the total reaction mixture was volatilized. Reaction temperatures 
as low as 850° C may be used to produce a low-lead product by increasing the 
CaCl2 and Si0 2 concentration to 4 and 2.5 pet, respectively. An equation for 
accurately predicting the effect of CaCl 2 and Si0 2 additions on chlorination 
results was developed for use in plant-scale tests. 

Research chemist. 
Metallurgist. 

Supervisory research chemist. 

All of the authors are with the Rolla Metallurgy Research Center, Bureau of 
Mines, Rolla, Mo. 



92 

References 

1. Carrillo, F. W. , M. H. Hibpshman, and R. D. Rosenkranz. Recovery of 

Secondary Copper and Zinc in the United States. BuMines IC 8622, 1974, 
58 pp. 

2. Davey, T. R. A., and G. M. Willis. Pb/Zn/Sn. J. Metals, v. 28, 

March 1976, pp. 16-19. 

3. Kenahan, C. B., R. S. Kaplan, J. T. Dunham, and D. G. Linnehan. Bureau 

of Mines Research Programs on Recycling and Disposal of Mineral-, 
Metal-, and Energy-Based Wastes. BuMines IC 8595, 1973, 54 pp. 

4. Montagna, D., and J. A. Ruppert. Refining Zinc-Base Die-Cast Scrap Using 

Low-Cost Fluxes. BuMines RI 7315, 1969, 10 pp. 

5. Powell, H. E., H. Fukubayashi, L. W. Higley, and L. L. Smith. Recovery 

of Zinc, Copper, and Lead-Tin Mixtures From Brass Smelter Flue Dusts. 
BuMines RI 7637, 1972, 8 pp. 

6. Powell, H. E., and L. W. Higley. Recovery of Zinc, Copper, Silver, and 

Iron From Zinc Smelter Residue. BuMines RI 7754, 1973, 15 pp. 

7. Powell, H. E., W. M. Dressel, and R. L. Crosby. Converting Stainless 

Steel Furnace Flue Dusts and Wastes to a Recyclable Alloy. BuMines 
RI 8039, 1975, 24 pp. 

8. Sullivan, P. M., D. H. Chambers, and P. J. Berney. Generation Preflux 

Solutions From Galvanizers ' Sal Skimmings. BuMines RI 5421, 1958, 
15 pp. 

9. U.S. Bureau of Mines. Zinc Industry, Monthly. Mineral Industry Surveys, 

Oct. 4, 1977, 9 pp. 



93 



RECYCLING OF POTLINING IN THE PRIMARY ALUMINUM INDUSTRY 

by 
W. D. Balgord 1 



More than 20 years ago the Bureau of Mines recognized the importance of 
recovering critical materials from wastes in the manufacture of primary alumi- 
num. Toward that end, it developed several flotation and leaching processes 
to recover fluoride values from spent potlining residues in the form of cryo- 
lite and other materials (1, 4-5) . 

Although several aluminum companies have reclaimed cryolite from pot- 
linings for a number of years, solid waste management on the whole continues 
to present the industry with two challenges: how to minimize the environ- 
mental impacts of its manufacturing processes, and how to maximize the recov- 
ery of nonrenewable resources from solid wastes. 

Both the industry and, more recently, the Environmental Protection Agency 
have recognized the importance of this situation and its unresolved nature, 
and two recent EPA studies specifically address aluminum industry solid waste 
management. One study (3), identifies reduction cell linings, skimmings, and 
floor sweepings as potentially hazardous waste sources. Another study (2), 
highlights the reclamation and disposal of reduction cell lining residues as 
one of several unresolved encironmental problems before the industry. 

In 1976, solid waste management came into sharper perspective with the 
passage of the Resource Conservation and Recovery Act (RCRA) (6) , with broad 
industry backing. The law raises significant questions for the basic mate- 
rials industries in the areas of recycling postconsumer waste and of disposing 
of hazardous process wastes . It has spurred interest within the aluminum 
industry in the concept of developing a single potlining recovery operation 
that might service several plants in one geographic region. Operated by 
possibly one or more independent entities, such facilities would reclaim 
chemicals and neutralize toxic components before ultimately disposing of 
innocuous residual materials . 

The RCRA gives the States a fixed timetable to develop comprehensive 
solid waste management plans. The effect of the regulations will be eventu- 
ally to prohibit outright dumping of hazardous wastes and, in all likelihood, 
to encourage the phasing out of certain practices currently associated with 
the onsite storage or disposal of spent potlinings. 

At this point it may be appropriate to list some barriers that may be 
inhibiting a comprehensive solution to the problem. Although the list 
reflects in part the views previously expressed by various professionals in 
the industry, it is the opinion of the writer that clear recognition of 
obstacles other than those of a purely technical nature is an important 
first step in their resolution. The list follows: 

President, Environmental & Resources Technology, Inc., Brookfield, Conn. 



94 

1. Scale economies for a complete recovery facility lie beyond waste 
volumes generated by a single plant. This factor has discouraged individual 
companies from undertaking the project unilaterally. 

2. Certain companies or certain plants use unconventional bath additives 
(for example, lithium) at additional costs. There may be reluctance among 
these companies to pool wastes in such a way as to dilute the additive through- 
out the industry. 

3. Concern over possible Federal antitrust action may have discouraged 
an organized effort by the aluminum industry to solve the problem jointly. 

4. There are already well-established sources of virgin materials. 

5. There is strong reluctance to adpot technology — and assume the 
royalty costs — developed by outsiders. 

6. Basic differences exist bwtween plants operating wet versus dry air 
pollution control systems in demand for type of fluoride (cryolite or aluminum 
fluoride) . 

7. Corporate resources have been heretofore claimed by other priorities. 

A survey of potlining recovery practices in the domestic primary aluminum 
industry (mid-1977) indicates that (1) approximately 800,000 tons of spent 
potlining exists at various plant locations and is being generated at annual 
rate of approximately 190,000 tons, (2) recovery technology at certain smelt- 
ers is adequate for partial recovery of chemical values (cryolite or carbon) 
or energy, (3) available technology can be used to recover high percentages of 
carbon, fluoride, and alumina from the annual production by economic and 
environmentally acceptable means, and (4) future technology may permit the 
recovery of substantial percentages of these values from the inventory. 

References 

1. Good, P. C, and W. G. Gruzensky. Extraction of Aluminum and Fluorine 

From Leached Potlining Residues. BuMines RI 7264, 1969, 9 pp. 

2. Hallowell, J. B. et al. Environmental Assessment of Primary Non-Ferrous 

Metals Industry Except Copper, Lead, and Zinc. Report under EPA Con- 
tract 68-02-1323, 1977. 

3. Leonard, R. P., and R. Ziegler. Assessment of Industrial Hazardous Wastes 

Practices in the Metal Smelting and Refining Industry. Volume II, 
Primary and Secondary Non-Ferrous Smelting and Refining. Calspan 
Report ND-5520-M-1, 1977. 

4. McClain, R. R., G. V. Sullivan, and W. A. Stickney. Recovery Aluminum and 

Fluorine Compounds From Aluminum Plant Residues. BuMines RI 5777, 1961, 
16 pp. 

5. McClain, R. S., and G. V. Sullivan. Benef iciation of Aluminum Plant . 

Residues. BuMines RI 6219, 1963, 17 pp. 

6. U.S. Congress. Resource Conservation and Recovery Act of 1976. 

Public Law 94-580, Oct. 21, 1976. 



95 



POWERPLANT FLY ASH AS A SOURCE OF ALUMINA 

by 
M. J. Murtha 1 and G. Burnet 2 



Nearly all the alumina produced today comes from bauxite found largely in 
the developing countries. As a result of fiscal and political activities in 
these countries, bauxite reserves have become less secure to consuming 
nations (2) . Some producing countries have nationalized mines , sharply 
increased royalties, assumed Government operation of new mines and plants, 
and promoted cartel- type joint price control. 

The cost of bauxite has increased substantially because of action by the 
International Bauxite Association (IBA) and because of higher freight and 
labor charges. In the past five years, the tax levy on bauxite from Jamaica, 
Haiti, and Surinam has increased from $2 per ton to $20 per ton of bauxite 
ore. These countries, with Guyana, supply about 80 pet of the bauxite from 
the U.S. aluminum industry; 90 pet of the bauxite used in this country is 
imported . 

The above factors have led to renewed interest in the development of 
processes for alumina production from raw materials other than bauxite. In 
some countries alumina is already obtained from other raw materials. In the 
U.S.S.R., for example, bauxite supplies are limited and alumina is extracted 
from nepheline, a waste product from the processing of nepheline syenite, to 
obtain apatite (3) . It would appear to be sound policy for the United States 
to develop processes for production of alumina from alternate materials in 
order to insure future availability (1) . 

One such material is fly ash from powerplants that burn pulverized coal. 
Currently, over 40 million tons of fly ash, much of which contains significant 
amounts of alumina, are generated annually in the United States. A process 
has been developed in which fly ash is sintered with lime and soda to form 
soluble aluminates that can be extracted and recovered. The amounts of lime 
and soda used must be precisely controlled to obtain maximum recovery; the 
required amounts depend upon the ratio of alumina to silica in the fly ash. 
Under optimum conditions, over 90 pet of the alumina in fly ash can be 
recovered . 

References 

1. Mitchell, W. D. Bauxite and Alumina. Min. Eng., v. 28, No. 3, March 1976, 

pp. 27-29. 

2. Patterson, S. H. Aluminum From Bauxite: Are There Alternatives. Am. 

Scientist, v. 65, No. 3, 1977, pp. 345-351. 

3. Shmorgunenko , and V. M. Sizyakov. Probl. Nefelin. Syr Ya, 1975, pp. 48-50. 



1 Assistant chemical engineer. 
2 Senior engineer. 
Both authors are with the Ames Laboratory, Iowa State University, Ames, Iowa. 



96 



A STUDY OF INDUSTRIAL WASTE MATERIALS EXCHANGES 
OPERATING IN EUROPE AND NORTH AMERICA 

by 
R. G. W. Laughlin 1 and H. Mooij 2 



The concept of the waste exchange is predicated on the old adage that "one 
man's meat is another man's poison," or as it might be restated today, "one man's 
garbage is another man's gold." Waste industrial materials may well prove to be a 
useful feedstock for another company. 

In order that companies may consider using a waste material, they must first 
know of its existence. This is achieved by a Waste Materials Exchange, which may 
be defined as a vehicle by which the availability of waste materials or byproducts 
is made known to potential users. Other, less formal definitions suggested to us 
during the study were "industrial flea market" and "industrial bargain hunters' 
press." 

Large companies with many processes and skilled chemical engineers are likely 
to find numerous recycling opportunities within their own manufacturing facilities. 
However, even engineers in large national companies are not likely to recognize all 
waste transfer opportunities outside their own industry. Thus, the concept of 
spreading the word about the availability of particular waste streams is attractive 
in that it increases the number of people examining possible uses for the waste. 

The basic philosophy behind the operation of a waste materials exchange is to 
help return much of what is now regarded as waste to an alternative industrial use. 
This may be achieved directly by one industry "buying" waste as a substitute raw 
material, or it may occur via some intermediary such as a reprocessor or scrap 
dealer. 

The objectives for such an exchange are — 

1. To save valuable raw materials, 

2. To save energy by not having to process raw materials, and 

3. To avoid environmental damage — 

(a) In the winning of raw materials and energy, and 

(b) In the avoidance of having to dispose of the waste. 

It would be very naive to imagine that a waste exchange will eliminate all prob- 
lems of waste disposal. There are many waste materials for which no use is ever 
likely to be found. A recent study (1-2.) of waste exchanges by Arthur D. Little 
for the U.S. Environmental Protection Agency concluded that, of a total industrial 
waste (generated by 14 major industrial sectors in the United States) of about 
206 million metric tons per year, 3 pet has potential value— a total of 6 million 
metric tons. Using a 10:1 ratio for Canada, some 600,000 metric tons of waste might 
be considered potentially transferable. 



Assistant Director, Department of Environmental Chemistry, Ontario Research Founda- 
tion, Mississauga, Ontario, Canada. 

Engineer, Solid Waste Management Branch, Environmental Protection Service, 
Fisheries and Environment, Canada, Ottawa, Ontario, Canada. 



97 

Wastes generally recognized as having components of potential value include 
those having high concentrations of recoverable metals, solvents, alkalis, concen- 
trated acids, catalysts, oils, and combustibles. A. D. Little's report included the 
following estimates of percentages of waste potentially transferable from four 
industry groupings: 

Transferable 
SIC No . Industry wastes, pet 

2911 Petroleum refining 63 

»„ , q ? Organic chemicals 22 

2884 Pharmaceuticals 17 

355 Small industrial machinery 17 

In the analysis of likely waste transfers in the chemical industry, A. D. Little 
concluded that transfers of waste materials are more likely to take place — 

1. From larger companies using continuous processes to smaller companies using 
batch processes, 

2. From basic chemical manufacturers to formulators, and 

3. From industries with extremely high purity requirements (for example, 
pharmaceuticals) to those with lower purity requirements (for example, paints) . 

The waste materials exchange will most probably be effective in encouraging 
transfers between different industries rather than internally within one industry 
where personnel are more aware of recycling opportunities . 

Costs for the operation of the existing waste materials exchanges are not well 
defined. In the cases of industrial societies and chambers of commerce, the costs 
were absorbed within general budgets . The United Kingdom exchange was funded with 
a $100,000 grant for a 2-year period of operation. St. Louis and the French waste 
exchanges were the only two exchanges making a charge for the use of the service. 
St. Louis makes a $5 charge for each waste listed. The French exchange, operated by 
the magazine Nuisances et Environment, charges normal, classified advertising rates 
for listing. Only the United Kingdom exchange has made any attempt to evaluate the 
impact of its operations. They assessed the first 125 wastes that transferred on 
the basis of "the value of the raw materials which these wastes replaced." This 
totaled $8 million for these 125 items. It can be argued that this is not a parti- 
cularly accurate analysis since no costs are assigned to transportation or any 
reprocessing of the wastes (if necessary) . However, no credit is taken for not 
having to dispose of the waste materials. If one rationalizes that the disposal 
credit and reprocessing costs would on average balance out, this figure of $8 million 
does at least indicate the approximate value of the exchange's operation. 

References 

1. Terry, R. C, Jr., J. D. Berkowitz, and C. H. Porter. Waste Clearinghouses and 

Exchanges. Chem. Eng. Prog., v. 72, No. 12, December 1976, pp. 58-62. 

2. Arthur D. Little, Inc. Waste Clearinghouse and Exchanges, New Ways for 

Identifying and Transferring Reusable Industrial Process Wastes . Report 
prepared for the U.S. Environmental Protection Agency under Contract No. 
6B-01-3241, October 1976, 34 pp. 



98 



BENEFICIATION OF STEEL PLANT WASTE OXIDES 
BY ROTARY KILN PROCESSES 

by 

H. Rausch 1 and H. Serbent 2 



Iron and steel making inevitably involves the generation of dusts which 
have to be taken off from the waste gases. Since the construction of the 
first filters for this purpose, metallurgists have been dealing with the 
question of the further use of these materials. The increased steel produc- 
tion, the improvements in filtration equipment, and thus the accumulation of 
greater quantities of finer dusts have continuously aggravated these problems. 
The recirculation of the zinc- and lead-containing materials, which are diffi- 
cult to handle, as well as their dumping are not solutions that can be gener- 
ally applied. In the blast furnace operation zinc causes difficulties which, 
particularly in the case of big furnaces, are of great economic importance. 
In the event of dumping, not only the nonferrous metals but also a consider- 
able quantity of iron is lost. Since the quantity of galvanized scrap treated 
in the steel plants will continuously increase, the difficulties resulting 
from the raw materials will hardly diminish. 

Processes suitable for the treatment of these waste oxides should fulfill 
the following prerequisites: 

1. Treatment of individual materials and mixtures, the chemical composi- 
tions and physical properties of which may vary within a relatively wide range 
during a short time. 

2. High metallization of the iron content of the raw materials and con- 
version into a lump-size product suitable as blast furnace feed. 

3. Removal of zinc and lead down to contents allowing a recirculation of 
the treated material to the material flow of the iron and steel works. 

4. Enrichment of the nonferrous metals in a flue dust that can be used 
by nonferrous smelters for recovery of these metals. 

Some of these demands are met by rotary kiln processes which have been 
known for a long time. Thus, zinc and lead are separated from ores and inter- 
mediate products by reducing volatilization according to the Waelz process, 
which has been applied in the nonferrous metal industry for about 50 years. 
Similar reducing conditions prevail in rotary kiln processes for production 
of sponge iron by using solid reductants unsuitable for the blast furnace. 



director of R & "0. 
2 Head of R & D department 



Both authors are with Lurgi Cheiuie und Huttentechnik GmbH, Frankfurt, 
Federal Republic of Germany. 



99 



ZnO+FeO+C 




Zn and CO 
flames 



Consequently, it was necessary to 
examine available technologies with 
regard to their utilization for the 
solution of this problem and to modify 
accordingly, if necessary. For this 
purpose, research and development work 
was carried out, from laboratory inves- 
tigations through industrial-scale 
trials . 



In 


the 


charqe 




1. ZnO 
2.C02 


♦ CO^Zn ♦ 

♦ C ^ 2C0 


C0 2 ~ 


3. ZnO 

1. FeO 
2C0 2 


♦ C 

♦ CC 

♦ C 


s=?Zn ♦ 

)i?Fe ♦ 
«i=?2C0 


CO 
C0 2 " 



In the freeboard 



1. Zn 

2. CO 



■ ZnO 



}0 2 - 

^o 2 ^co 2 



Figure 1 shows the principle of the 
operating method taken into considera- 
tion. The kiln charge containing solid, 
carbonaceous reductant travels through 
the inclined kiln in countercurrent flow 
to the oxidizing kiln gases in the kiln 
freeboard. Zinc and oxide are reduced 
under the decisive influence of the 
Boudouard reaction. The zinc then 
emerging as metal vapor from the charge 
together with carbon monoxide is oxidized 
in the free kiln space and leaves it 
together with the waste gas in the form 
of a flue dust which can be separated 
from the latter. The CO emerging from 
the material surface causes the separa- 
tion of the oxidizing from the reducing atmosphere prevailing above and within 
the charge. 



3.Fe0 *C^Fe ♦ CO 



FIGURE 1. - Zinc volatilization and re- 
duction of iron oxides in the 
rotary kiln, schematically. 



The SL/RN process and the Waelz process represent extreme cases with 
regard to material preparation and the lump size of the dezincified material. 
Between these extreme cases can be classified the rotary kiln processes in 
which, for example, green pellets are dried before they are charged to the 
kiln. None of these processes can avoid the accumulation of certain quanti- 
ties of fines. Thus, even in the version of the SL/RN process used by Nippon 
Kokan about 5 pet minus %-inch fines are obtained which are also briquetted 
there. As compared with the nonbriquetted coarse material, the briquets can 
be better stored and transported. 

The process selection depends both on the iron content and on the zinc 
and lead content of the waste oxides. With iron contents of about 55 pet and 
relatively low contents of nonferrous metals, the SL/RN process including its 
material preparation is to be given preference. In the reverse case, which 
is usual, the Waelz process offers greater advantages. It affords a greater 
flexibility as compared to the variations occurring for these materials, uses 
a simpler rotary kiln without air admission tubes, and thus represents a 
relatively cheap zinc bleed-off for the iron industry. 



100 



"CANMET" WATER RECOVERY SYSTEM FOR INDUSTRIAL EFFLUENTS 

by 
H. A. Hamza 1 and N. E. Andersen 2 



With the current rapidly increasing usage of water for public supply and 
for industrial purposes, there have been corresponding increases in effluent 
volumes. 

Industry uses vast quantities of water for processing, transport, steam 
generating, heat transfer, solvent extraction, and fire protection. Every 
plant does not necessarily use water in all these ways; instead, water usage 
varies widely among different types of industry. In the mining industry, for 
example, water may be used directly in mining as a dust suppressant, for 
hydraulic mining, and/or for ore benef iciation. Hydraulic mining consumes 
especially large volumes of water; for example, the Florida pebble phosphate 
industry uses about 7 tons of water for every ton of ore mined. Similar con- 
sumption has been reported for the hydraulic mining of a Canadian coal. Coal 
preparation requires up to 5 tons of water for each ton of coal processed. In 
froth flotation, a common operation in mineral processing, the weight of water 
being used may be as high as 7 times the weight of ore being treated. In a 
pulp mill, as much as 20 tons of water must be clarified to produce 1 ton of 
pulp. Gas processing plants and oil refineries consume vast quantities of 
water for steam production and cooling purposes. 

Plant effluents usually contain a high level of dissolved solids, metal 
ions, residual process reagents, chemical complexes, etc., in addition to 
suspended solids, which generally exist in a colloidal state. In most cases 
these streams are discharged to tailings impoundments where the solids are 
retained and the supernatant is treated prior to discharge into water courses 
or recycle to the plant. Depending on the nature of the process, the water 
may become unsuitable after one or more recycles. Very often, however, the 
addition of makeup water will maintain soluble constituents at tolerable 
levels and thereby allows continuous circulation of water. 

The degree to which the final discharge can be reduced by recycling is 
dependent on the process requirements, the treatability of the effluent, and 
ultimately, the efficiency of treatment. The degree of recycle practices by 
base metal mills in Canada, for example, has increased dramatically in recent 
years, and recycling now provides 60 pet or more of process requirements. 
Future increases in recycling of water will be brought about not only by 
increasing water costs but by environmental regulations. For example, the 
U.S. Environmental Protection Agency (EPA) Effluent Guidelines and Stand- 
ards (1) promulgated May 13, 1976, demand, zero effluent discharge from coal 



^Research scientist, flocculation studies. 
Processing scientist. 
Both authors are with the Department of Energy, Mines and Resources, Western 
Research Laboratory, Edmonton, Alberta, Canada. 



101 



preparation plants. This requires fully closed water circuits and prohibits 
discharge of process water from a wash plant, tailings pond, slurry pond, or 
other area of impoundment into the surrounding environment. All process water 
must be treated in such a way that its effectiveness as a washing medium is 
maintained. Because of the many types of contaminants accumulating in a coal 
processing medium, this requirement cannot always be fully satisfied. Land- 
use priorities have made large tailings ponds increasingly objectionable, and 
as such, the water clarification system will form a critical part of any coal 
benef iciation plant. 

The Canmet water recovery system has been successfully applied to a 
variety of clay and coal washery tailings. Characteristics of some typical 
effluents are summarized in table 1. Using the previously described procedure 
for flocculant selection and evaluation, three superior flocculants for each 
effluent are indicated in table 2 . The ranking order shown is based on the 
flocculant cost per unit of settling rate and may change if other factors are 
considered. Flocculant cost depends on the dosage required and the commercial 
price of the flocculant. 

TABLE 1. - Effluent characteristics 





CR 


CP 


FP 


HC 




Coal froth 


High-sulfur 


Pebble 


Thermal coal — 




flotation 


coal slimes 


phosphate 


fine tailings 




tailings 




slimes 






2.09 


1.79 


2.70 


2.30 


Solids content . . . .wt-pct . . 


0.6 


4.0 


2.6 


4.3 




45.6 


43.0 


- 


70.0 


Zeta potential mv . . 


-18 


-20 


- 


-21 


Ions in solution, ppm: 










Ca +2 


30 

9 

42 


80 
28 
91 
9 
700 
20 


47 

13 

6 

54 
10 


488 


+ 9 

Mg z 


205 


Na 


154 


K 


33 


SOtf 2 


2440 


CI" 


5 


PH 


8.2 


6.9 


7.6 


7.2 


Median particle size..um.. 


18 


25 


1.2 


12 



In summation, it may be stated that most water-circuit closing problems 
can only be effectively dealt with through a thorough knowledge of the solid- 
liquid system at hand, together with pilot studies including jar tests and 
familiarization with the nature and technology of flocculants. 



102 



TABLE 2. - Ranking of selected flocculants 



Sample 


Flocculant 
ranking * 


Flocculant 


Manufacturer 


Settling rate at 
optimum dosage, 
in/hr 




< 
< 
< 

< 


' NAp 
1 
2 
3 

' NAp 

1 
2 

, 3 

' NAp 

1 
2 

I 3 

' NAp 
1 
2 

. 3 






7.1 




Hereof loc 819.2.... 
Poly-floc 1100 

Superfloc S3803 

Percol 352 

Praestol 2935/75... 
Superfloc N100S 


625 


CR 
CP 


Allied Colloids .... 
Betz 


535 
738 

12.6 
2,590 
2,590 


FP 


NAp 


2,340 

.5 
863 
2,070 


HC 


Allied Colloids .... 


1,725 

2.4 
425 
525 






305 



NAp Not applicable. 

banking based on flocculant cost per unit settling rate, 



Reference 



1. U.S. Environmental Protection Agency. Coal Mining — Effluent Guidelines 
and Standards. 40 CFR, 1978, pt. 434, p. 847. 



103 



SCRAP METAL 
OVERVIEW 

by 
H. Cutler 1 



Although there have been significant technological changes affecting min- 
eral waste utilization since the first Bureau of Mines-IITRI Symposium in 1968, 
we somehow find ourselves today faced with many of the problems that prompted 
that meeting. 

Even a casual review of the proceedings of the five previous symposia 
provides a stark contrast and insight to the changes in technology and priori- 
ties in waste utilization that have occurred. 

As a point of reference, the ferrous scrap market in 1968 was weak, with 
domestic purchased scrap receipts totaling 36.7 million net tons. The annual 
average composite price for No . 1 Heavy Melting Scrap that year was only 
$25.86 per ton, its lowest level since 1946; the No. 2 Bundle price was a 
mere $20.11. The open-hearth furnace was still king, but in 2 years it would 
lose that title to the basic oxygen furnace. The electric furnace was begin- 
ning a modest but steady gain that in 1975 resulted in its also overtaking the 
open hearth in steel output. Equaling a previous record, 131.5 million net 
tons of raw steel was poured in 1968: 50.1 pet by open hearths, 37.1 pet by 
BOF's, and 12.8 pet by electrics. Domestically, the United States mined 96.2 
million tons of iron ore and imported 49.2 million net tons, or 34 pet of the 
total iron ore needs of this country. 

At that first symposium, the Bureau's then Deputy Director, Earl T. Hayes, 
took the point of view "... that we have failed thus far in an essential mis- 
sion, which is to convince the general public that mineral resources are not 
inexhaustible, that depletion is real and permanent in the case of many ores 
and that conservation of mineral byproducts is an urgent necessity..." 

There was certainly mounting evidence in the Nation's dumps, landfills, 
countryside, vacant lots, and city streets that Mr. Hayes was in part correct. 
I say "in part" because the public crescendo was building that would lead to 
the first Earth Day in 1970. In this instance, I think it is fair to say that 
the people were pushing Government leaders to take action — the Government was 
not pulling the people. 

The public mood that was forming at the time of the first symposium was 
in the process of erupting when the second was held, as characterized again by 
Mr. Hayes when he said, "important changes have taken place since the first 
symposium. . . At that time the issue of environmental quality had not assumed 

Executive Director, Institute of Scrap Iron and Steel, Inc., Washington, D.C. 



104 

the grip it now holds on the public consciousness. President Nixon ... has 
designated the 1970 f s as a now or never decade in which we must move to 
restore the quality of our air, our water and our land ..." The President 
also said that the seventies "absolutely must be the years when America pays 
its debt to that past...," a debt, in the case of metallic scrap, we are still 
increasing. 

President Nixon had made that statement 3 months earlier on January 1, 
1970, when he signed into law the National Environmental Policy Act, which 
created the Council on Environmental Quality and required each Federal agency 
to prepare a statement of environmental impact in advance of each major action, 
recommendation, or report on legislation that might significantly affect the 
quality of the human environment. 

Almost a month to the day following the second symposium, Earth Day was 
held. Although the Federal commitment was significant, the tempo of Earth Day 
indicated that much of the initiative for environmental action was still com- 
ing from the people. 

It was at the second symposium that Hollis M. Dole, then Interior Depart- 
ment Assistant Secretary for Mineral Resources, pointed out that secondary 
materials and metals represented "our only growing resource," a phrase that 
would be quoted often. 

During the summer of 1970, still on the crest of public momentum, the 
Council on Environmental Quality transmitted its first annual report to the 
Congress and stated that "maximum recycling and reuse of materials are neces- 
sary to reduce the growing volume of solid wastes that must be disposed of." 

Two months later, the Congress passed and President Nixon signed into law 
the Resource Recovery Act of 1970 — waste disposal of the sixties became 
resource recovery in the seventies. This act also created the National Com- 
mission on Materials Policy, which subsequently prepared a major report only 
to find that its recommendations were virtually ignored by its creators, the 
Congress. 

By the end of 1970, through the executive reorganization plan, a new 
Government entity was created — the U.S. Environmental Protection Agency, and 
within that agency, the Office of Solid Waste Management Programs. 

Thus in just one year, the Nation was exposed to the most far-reaching 
series of actions dealing with environment and solid waste in its history. 
It was a time of positive anticipation for those who were committed to the 
benefits and necessity of increased recycling. 

Based on these events, Mr. Hayes may have been premature to admit failure 
in 1968. Public consciousness probably began to accelerate with the passage 
of the Highway Beautif ication Act of 1965, and there was considerable atten- 
tion to the problem of abandoned and junked autos at that first symposium. 

William A. Vogely, the Bureau's then Assistant Director for Mineral 
Resources Development, observed, "Other obsolete scrap cycles are quite 



105 



inefficient and may involve considerable spillover damages to society as a 
whole, as with junk autos..." 

While the Bureau recognized the problem, it also realized that junk autos 
represented a resource not to be wasted, but to be recycled. And although 
there was some minor reference to the then relatively new technique of shredd- 
ing, the focus of automobile scrap was the No. 2 Bundle — a drudge on the 1968 
market at $20 a ton. 

As an aside, going back now to 1970, there was at least one projection 
made at that meeting and it is always interesting to see how close forecasters 
come to reality. Granted projections are a risky exercise, but that risk is 
to the individual who chooses to indulge in calculations of the future. In 
this particular case it was projected that shipments of iron and steel cast- 
ings, reporting at 17.6 million net tons in 1968, would double by 1980. Pre- 
liminary figures show that 1977 shipments were at 17.6 million net tons, and 
shipments over the past 10 years (1968-77) have averaged 17.6 million net 
tons. With 3 years to go, I'm sure the ferrous scrap and foundry industries 
are hoping that this 1970 prediction will come true. 

At that meeting, Bureau researchers reported on their investigations of 
foundry iron production from automobile scrap, pollution-controlled incinera- 
tion of automobile hulks, and the recovery of nonferrous metals from shredder 
residues. It is also interesting to note the concern expressed with high 
freight rates for ferrous scrap and the shortage of gondola freight cars in 
which to ship scrap — two problems that are definitely yet with us. 

The relatively new agency, EPA, was also represented at the 1972 sympo- 
sium. The then Assistant Administrator of Categorical Programs, David C. 
Dominich, stated, "... We are concerned with the economics of resource recov- 
ery, with the present legal discrimination on secondary materials imposed by 
freight rates, and with other market factors that have inhibited a greater 
degree of resource recovery in the past . We understand that the problems of 
greater material recovery cannot be solved solely by technological advances — 
the market for reclaimed resources must also be responsive." 

Attention has shifted to the municipal solid waste stream, and the fact 
that we have more of it than we knew what to do with, but we also knew that 
we had to do something about it. 

Fred Berman, then president of the Institute of Scrap Iron and Steel, 
summed up the scrap industry's feeling, which still holds, when he said, 
"Certainly our objective is recycling, but our attention must be directed 
first to the need for more demand, not more supply." 

Two researchers from Battelle Columbus Laboratories who presented a paper 
offered the caution, "Recycling is so obviously appealing that many people are 
instantly taken with the idea. They see it as a simple and obvious way to 
solve problems of resource depletion and waste disposal. Although it is true 
that recycling is a potential solution, it is not simple or obvious. There 
are many obstacles to the effective implementation of the recycling concept 
on a scale larger than the present one." 



106 

The junk automobile was still a concern in the spring of 1972. The fact 
that 1971 had been a relatively poor year for total scrap demand clearly 
influenced the problem, and two Bureau researchers concluded that "regardless 
of the solutions to abandonment which are eventually chosen, and there may be 
as many as there are local governments, it appears that government programs 
must be part of the solution. While changes in technology and market values 
will certainly help the movement towards a solution, it simply does not appear 
that the marketplace, by itself, will solve the auto abandonment problem." 

To the contrary, the strong demand for ferrous scrap in 1973 and 1974 
indicated that the marketplace could solve the problem, if there was a sus- 
tained demand for the product. 

The impact of municipal refuse in this country was demonstrated at the 
fourth symposium by the number of presentations dealing with solid waste. 
While there had been some mention of converting this "resource" to a fuel in 
1972, it was obvious in 1973 that the United States had experienced an energy 
shock and thus more interest was engendered. 

Further reports were presented by Bureau personnel on research dealing 
with auto and ferrous refuse scrap in cupola iron production and the separa- 
tion of nonferrous metal concentrates from auto shredder nonmagnetive residues. 
The use of cryogenics as a processing technique was also discussed. 

Like the previous seminar, 1976 again placed heavy emphasis on municipal 
solid waste and included many papers on resource recovery and energy systems 
throughout the United States and in other countries. 

Of particular interest to the session on scrap metals was the presenta- 
tion by an A. T. Kearney, Inc., associate entitled, "Scrap Demand Versus Newly 
Available Supply 1975 - 1985." This paper concluded "It appears that the 
domestic scrap supply can support the forecasted levels of mill and foundry 
operations and the resulting derived demands. Recall that the total demand 
for scrap did not include export demand, which for the three years 1972-74 
averaged nine million tons, excluding shipwrecking operations. From a pre- 
liminary net balance results, this level of export activity cannot be sup- 
ported 'from the supply of newly available ferrous scrap if the demands for 
domestic consumption are to be met." 

It was further estimated by that paper that 1976 domestic raw steel pro- 
duction would reach 141 million net tons, resulting in steel shipments of 
128 million net tons. However, when the year was over, the final figures 
revealed that only 98.5 million tons of steel were poured and 89.4 million 
tons of steel was shipped. The projection was off by some 30 pet. 

There is little doubt that the record domestic demand for ferrous scrap 
in 1974 prompted this and numerous other studies dealing with the "future 
availability" of iron and steel scrap. Although the marketplace went into a 
downward spiral following that record year, the forecasts of scrap shortages 
continued even though domestic demand dropped by 28 pet, or nearly 15 million 
tons. 



107 



To conclude this overview, I would like to cite the remarks of Murray A. 
Schwartz in the foreword to the proceedings of the first symposium. He stated 
that "technological solutions" to the problems of waste disposal are the 
"objectives of this symposium." He expressed the hope that the meeting "will 
act as a turning point in our national thinking towards a positive approach 
to a number of problems including scrap accumulations and natural resource 
depletions." 

While I would not deny the importance of technological innovation and the 
progress that has been reported at the five previous symposiums, what is 
needed is an equally innovative approach to the economics of the marketplace. 
This point, as I noted earlier, was made by EPA's David Dominich. The market- 
place discrimination he described continues to plague us and becomes ever more 
apparent as our ability to separate metallic waste becomes more sophisticated. 

The marketplace is affected by economics; the roots of those economic 
problems can be found in the law; and the law is the domain of politics. 

To paraphrase Earl Hayes, we have failed to convince this Nation's 
Government leaders that mineral resources are not inexhaustible, that deple- 
tion is real in the case of many ores, and that conservation of mineral 
byproducts is an urgent necessity. If it was an urgent necessity in 1968, 
and I share Mr. Hayes' belief that it was, the urgency should be unmistakable 
today. 



108 



THE BACKLOG OF IRON AND STEEL DISCARDS IN THE UNITED STATES 

by 
H. Cutler 1 



The ferrous scrap marketplace is a classic textbook example of the 
economist's supply and demand factor at work. A freely traded commodity, 
scrap is subject to sharp peaks and valleys and is characterized by a large 
number of highly competitive suppliers and a relatively small number of 
buyers . 

The erratic nature of the scrap market is caused in part by the way in 
which the commodity is purchased, generally on 30-day contracts. Conversely, 
the other major raw material inputs to the iron and steel making processes are 
generally either owned or controlled by the ultimate consumer, or long-term 
contracts are utilized, providing a sense of stability. 

A third characteristic of the industry centers around how obsolete scrap 
gets to the processing plant. Through an informal system of collectors and 
peddlers, who have as their motivation the price paid for the "old iron" at 
the processor's scale, discarded scrap moves to the scrap plant. In some 
cases, 90 pet of a processor's intake of materials may come from peddlers. 
One processor reports dealing with up to 100 different peddlers daily. 

The collection system functions at its best when there is a sustained 
strong demand for scrap and at its worst when the market for scrap is 
depressed. However, unlike other raw materials, there is no way to stop the 
generation of metallic discards. They are not intentionally produced. Scrap 
happens, throughout the country, where there are people. While you can stop 
the production of iron ore, coal, or limestone by closing the mine, scrap 
keeps coming. Rather than closing, the mines aboveground grow larger and 
larger as society's discards pile up. 

With rare exceptions, the late fifties through the sixties and into the 
seventies were not outstanding years for the scrap-processing industry. Dur- 
ing the 15-year span from 1958 through 1972, the average of the annual average 
composite price for No. 1 Heavy Melting Steel Scrap was $33.23 per ton. 
Domestic purchased scrap receipts averaged only 31.7 million net tons and 
exports averaged 7 million net tons during the 15-year span. 

This was to change, however, in 1973 with a worldwide increase in the 
demand for steel and subsequently in the need for scrap. New records for both 
domestic and export purchases of scrap were established that year, 44.7 mil- 
lion net tons and 11.3 net tons, respectively. 

Executive Director, Institute of Scrap Iron and Steel, Inc., Washington, D.C. 



109 



The domestic record was to stand for only 1 year, since purchases 
increased an unprecedented 15 pet to 51.3 million net tons in 1974. As a 
result of export restrictions imposed in mid-1973, exports of ferrous scrap 
in 1974 dropped to 8.7 million net tons. (Those restrictions were lifted on 
December 31, 1974.) 

In 1973 and 1974 scrap iron began flowing at a rate never experienced in 
this country. As a result, many scrap consumers alleged that the scrap- 
processing industry lacked the capacity to process the scrap required and 
that there was not sufficient scrap available to meet both the domestic and 
the export demand. 

Unlike other recent studies dealing with scrap iron availability, this 
study makes no predictions about the future behavior of the scrap inventory. 
It is apparent, nevertheless, that the size of the scrap reservoir in the 
future will depend on a number of interrelated factors, paramount among which 
will be technological developments and practices in the iron and steel making 
industries (domestically and internationally); rates of technological, eco- 
nomic, or physical obsolescence of ferrous metal products; and the long-term 
relationship between the total cost of producing steel from iron ore as 
opposed to ferrous scrap . 

No forecast is required, however, to identify a pool of obsolete ferrous 
scrap available as of December 31, 1975 (636.2 million net tons as shown in 
table 1), which is sufficient in size to satisfy fully the total purchased 
scrap requirements, at the 1977 level, of the entire U.S. steel and foundry 
industries, plus the export demand, for nearly 14 years, or until 1992. And 
this does not consider the millions of tons of new obsolete scrap generated 
each year and not recycled. 

TABLE 1. - Total inventory (adjusted for corrosion loss) by region 

(Thousand short tons) 



Census region 



1955 

inventory 

(1) 



1956 
additions to 
inventory (2) 



Total inventory 
through 1975 
(1) + (2) 



New England 

Middle Atlantic. . . , 
East North Central 
West North Central 
South Atlantic. 
East South Central 
West South Central 

Mountain 

Pacific 

Total 



40,800 
24,705 
58,393 
71,494 
59,891 
6,363 
62,511 
23,208 
26,951 



28,611 
17,293 
40,940 
50,080 
42,023 
4,403 
43,644 
16,125 
18,782 



69,411 

41,998 

99,333 

121,574 

101,914 

10,766 

106,155 

39,333 

45,733 



374,316 



261,901 



636,217 



110 

Obviously, most previous forecasts of future scrap shortages have not 
scientifically calculated the tremendous reservoir of obsolete iron and steel 
scrap which has accumulated through the years . 

While the fact that we have a 636-million-ton backlog of ferrous scrap 
for recycling could be seen as a national asset, it is, in reality, a national 
tragedy. The fact that an additional 100 million tons of recyclable scrap 
iron has been allowed to rust away is a national disgrace. Had that 100 mil- 
lion tons been recycled, the energy savings alone in making new steel from 
this material would be equivalent to 14 billion gallons of gasoline. The 
636-million-ton reservoir, if used instead of iron ore to make new steel, 
represents an energy saving equivalent to more than 89 billion gallons of 
gasoline. 

It is obvious that this country must come to grips with the public policy 
questions that have led this Nation to virtually ignore its manmade resources 
while depleting irreplaceable virgin resources whether they be mined here or 
imported from around the world. Public policy makes it more economically 
attractive to mine and transport raw material from all over the world than 
to use readily available domestic ferrous scrap from within American borders. 

Actions should be directed toward increasing the use of iron and steel 
scrap in order to avoid this continual buildup of our naturally acquired and 
internally generated scrap resources, and their eventual loss to the system 
because of disuse. The energy savings alone make this step mandatory for the 
good of the American people. 

In terms of energy and mineral savings, and the improvement in environ- 
mental quality, there is much to be gained when there is a greater use of 
ferrous scrap in the making of new iron and steel products. The challenge 
before us is to take this backlog of discarded metallics from a social 
liability to its rightful and proper place as a national economic asset. 



Ill 



BARRIERS TO THE USE OF SECONDARY METALS 
by 
B. M. Sattin 1 



The recycling of scrap materials has become a much-discussed topic in 
recent years. Many benefits from recycling have been identified, including 
decreased dependence on finite natural resources, reduction of solid wastes 
that would otherwise require land- intensive disposal, energy savings, reduc- 
tion of environmental problems caused by mineral extraction and processing, 
and many others. 

The fact that these benefits have not been fully realized is also the 
subject of considerable discussion, which often focuses on various Government- 
imposed obstacles, or barriers, to recycling. Several of these so-called 
barriers were identified by previous studies or brought to the attention of 
Congress and Federal regulatory agencies by the trade associations represent- 
ing the scrap-processing industry. No study, however, has previously 
attempted a systematic search for these barriers or has developed cost esti- 
mates of the impact of more than two of the barriers already identified. 

This article is a condensation of a report (1) resulting from a 2-year 
study effort funded by the Bureau of Mines to identify barriers created by 
government at the Federal, State, and local levels to the reuse of secondary 
metals. Once these barriers were identified, basic information concerning 
them was developed so as to permit the formulation of legislation to lessen 
the impact of those barriers found to have a significant effect on the 
recycling of scrap metals. Forty-one potential barriers were identified 
and ranked, and the five most important were analyzed in detail. 

Since most of the barriers identified had been originally intended to 
serve some useful and valid purpose, their current negative impact on the 
scrap recycling industry is an unintended result. The simple fact that a 
barrier has a detrimental impact on recycling is not reason enough, standing 
alone, to remove that barrier. 

Although it is not suggested that all the identified barriers be repealed 
or amended, certain of them could be freshly evaluated in order to determine 
the following: 

1. Is the law or regulation still necessary? 

2. Is the purpose for which it had been intended being served? 

3. Is the purpose served sufficiently important and is the intended 
effect sufficiently large to override the negative effect on recycling? 



Research associate, JACA Corp., Fort Washington, Pa. 



112 

4. Even if the answers to the three questions above support the law or 
regulation, are some other means of accomplishing the intended purpose avail- 
able that will not have as great a negative impact on the recycling industries? 

Five high-priority barriers were studied in depth, and costs per ton of 
raw steel or secondary aluminum were calculated. Freight rate differentials 
were found to create a $0.72/ton barrier to the use of scrap iron and steel 
and a $3. 31/ ton barrier to the use of scrap aluminum. The percentage deple- 
tion allowance created barriers ranging from $1.05/ ton to $3. 21/ ton to the use 
of scrap iron and steel and from $3. 06/ ton to $5. 74/ ton to the use of scrap 
aluminum. Automobile titling laws created barriers in the six States surveyed 
ranging from $0.15/ ton to $1.22/ton against the use of scrap iron and steel. 
Procurement policies and pollution control requirements were not found to 
create barriers to the use of secondary metals . Subsidies to the secondary 
metals industries were found to result in only negligible increases in scrap 
utilization in the short term, but long-term increases in scrap aluminum 
consumption could occur. 

The in-depth analysis of five high-priority barriers demonstrates that 
legislative actions have disadvantaged the secondary metals industries in 
relation to the virgin metals industries. Such factors as the extent and 
type of assets held by firms within the virgin metals industries permit 
utilization of some Federal subsidies which, while theoretically available 
to the secondary industries, are seldom actually applied because of size and 
extent of assets. Additionally, certain Federal subsidies are available only 
to the virgin metals industries because these subsidies have been designed 
to benefit only these industries. It may be concluded that, to the extent 
that subsidization is greater in the virgin metals industries than in the 
secondary metals industries, investors will favor the virgin metals industries. 
Potential for the expansion of firms within the secondary materials indus- 
tries is thereby limited. 

Paucity of data and lack of specificity and disaggregation of data make 
it impossible to measure the effects of any tax subsidy other than the per- 
centage depletion allowance. However, the study did show that any subsidiza- 
tion of the secondary metals industries would result in negligible increases 
in scrap consumption. Similarly, elimination of the percentage depletion 
allowance would, in the short run, produce little change in scrap consumption. 

The study also showed that subsidization of the secondary aluminum indus- 
try may, in the long run, produce positive effects on scrap utilization. 
Technological developments in the steel industry tend to make demand more 
responsive to price changes. Reduction or elimination of the depletion allow- 
ance under these conditions may have a greater long-run effect on scrap usage. 
It is concluded that more data would have to be made public by the primary 
metals industries to construct a cost-benefit analysis of the long-run effects 
of subsidization and elimination of subsidization in these industries. 

Since auto salvage is performed for the used parts as well as the ferrous 
content of the vehicle, removal of unnecessary costs associated with automo- 
bile titling laws, such as reducing or eliminating the titling costs and 



113 



impoundment periods for cars of no value (as is done in Ohio) and eliminating 
notarizing costs, may have a small positive effect in moving more abandoned 
cars to auto salvagers for their used parts content without incurring any cost 
to the State. Effectiveness of proposed legislation would have to be deter- 
mined by the results of an analysis of what cost and level of effort is nec- 
essary to strike an appropriate balance between protection of private property 
rights and the rights of society to an aesthetic environment. 

Transportation rates and possibly services have been shown to favor the 
movement of virgin inputs into raw steel and primary aluminum and disfavor the 
movement of scrap iron and steel and aluminum. While the economic impact of 
these disparities is small in comparison to the prices of the commodities 
involved, they are perceived as significant barriers by scrap shippers. Con- 
sequently, more scrap is moving from processor to consumer by truck and less 
by railroad. Besides limiting the shipping radius of prepared scrap, this 
trend may have repercussions for the railroads that profit from scrap carriage. 

Procurement policies and pollution control requirements were not found 
to mitigate against the use of secondary metals. 

Economic analysis of barrier removal or subsidization of scrap utiliza- 
tion were found not to increase scrap use significantly in the short run, but 
longer term effects were noted as possible for scrap aluminum. 

Based on the conclusions and observations recorded in the study, the 
following recommendations were made: 

1. No form of direct subsidy should be given to the producers of steel 
scrap. However, it is recommended that a cost-benefit analysis of the long- 
run effects of subsidization of the secondary aluminum industry be undertaken. 

2. The question of removing subsidies to the steel industry should be 
addressed, with full analysis of any side effects, taking into account that 
in the future a significant portion of steel production will be generated by 
relatively new technology. 

3. As detailed information on the assets of primary and secondary metals 
firms in the aluminum and steel industries becomes a matter of public record, 
comparative studies should be undertaken to measure the total effect of all 
forms of tax subsidization in each industry. 

4. Unnecessary costs associated with automobile titling laws should be 
removed by each State. This process may be facilitated by the development of 
model legislation that may be adopted by each State. 

5. Alleged disparities in railroad transportation services to the virgin 
metals producers and the scrap handlers should be investigated by the Inter- 
state Commerce Commission (ICC) . 



114 



6. The ICC should establish criteria for evaluating point-to-point 
rates for hauling scrap metals and virgin inputs into primary metals by rail. 
These criteria should be applied when assessing new rate applications or 
protests against existing rates. All rates falling below a certain revenue- 
variable cost ratio should be ordered raised (with 1.00 as an absolute minimum 
ratio), and all those above a certain ratio (perhaps 2.00) should be ordered 
reduced. 

Reference 

1. Commins, J. A., V. R. Hathaway, E. F. Palermo, B. M. Sattin, and 

M. A. Timothy. Barriers to the Use of Secondary Metals, BuMines 
OFR 129-77, 1977, 535 pp.; available from National Technical Informa- 
tion Service, Springfield, Va., PB 271 814/AS. 



115 



OPTIONS FOR THE COLLECTION AND RECOVERY OF HOUSEHOLD APPLIANCE MATERIALS 

by 
E. A. Kinne 1 



A great deal of publicity has been given to processing municipal wastes, 
recycling beverage containers, and recovering automobile resources. Yet there 
has been little consideration given to recycling appliances. Obsolete appli- 
ances represent a large and potentially valuable resource. In the next 10 
years, 2 to 2.6 million tons of ferrous metals alone could be recovered annu- 
ally from recycled appliances (2_) . 

In 1972, a document prepared by the Institute of Scrap Iron and Steel 
(ISIS) (1) stated that there were 350 million major appliances in use in the 
United States, and that they were being discarded at the rate of 21 million 
units annually in 1971. The annual rate was expected to rise to 29 million 
units by 1980. 

This document also stated that very few appliances were being recycled. 
The reasons given were — 

1. The variety of materials contained in major appliances that require 
extensive processing to obtain quality scrap for steelmaking. 

2 . The values of units as scrap were relatively small . 

3. The high cost of handling and transportation relative to the scrap 
value . 

4. The lack of a centrally located continuous source of supply for a 
processor. 

In addition to these limitations, some scrap specifications include a 
provision specifically prohibiting the inclusion of appliances. 

The situation as outlined in the 1972 ISIS study still persists in many 
locations despite significant changes in technology, markets, legislation, 
and public attitudes. The service life expectancies of appliances are shown 
in table 1 . 

There are many ways to approach handling of appliances for recovery. 
The value to the original owner has declined to near zero when it is ready 
for discard. Interest in the product has changed from one of utility to one 
of disposal. Usually this means the easiest disposal, not necessarily the 
most cost effective approach. 

Consumer industry marketing representative, United States Steel Corp., 
Pittsburgh, Pa. 



116 



TABLE 1. - Service-life expectancy under one owner of selected 
appliances acquired new and acquired used 1 



Item 



Service life 
July 1972, 
years 



Standard error 

July 1972, 
years 



Range 



.2 



Electric: 

New. . . . 

Used... 
Gas: 

New .... 

Used . . . 



Refrigerator: 

New , 

Used , 



Freezer : 

New. . . 
Used.. 



Dishwasher : 

New , 

Used 



Clothes dryer: 
Electric: 

New 

Used 

Gas: New. . . 



Washing machine (automatic) : 

New 

Used 



Television: 

Black and white: 

New 

Used 

Color: New 



•New and used are not additive. 
■Free-standing only. 
Includes both built-in and portable. 



12.1 
5.6 

13.5 
6.6 



15.2 
7.4 



20.4 
9.3 



11.1 
6.8 



10.7 

5.4 

12.0 



1.4 
.7 

1.4 
.7 



.9 
.6 



4.0 
1.9 



1.4 
1.4 



13.7 


1.3 


5.1 


.8 


12.8 


1.8 


10.8 


.5 


4.5 


1.8 



.5 

.4 

1.4 



Source: Home Economics Research J., v. 3, No. 3, March 1975 



117 



Because the ferrous fraction is such a significant factor in appliances, 
it could be useful to review the disposal of other consumer products fabri- 
cated from steel. I would like to suggest a three-category approach for 
analysis of steel consumer products destined for disposal. 

1. Containe rs . — Hand-carried products including food and beverage con- 
tainers and other items which fit into a garbage bag. 

2. Appliances . — Deliverable products which may be moved manually, includ- 
ing discarded storage cabinets, files, furniture, and tools. 

3. Automobiles . — Heavy products which require a machine assist to move, 
including home construction materials. 

Just as each category of product reaches the consumer in a different 
manner, the path for return differs. Quantities must be accumulated along 
each step of return so that it is possible to optimize utilization of produc- 
tivity of people and equipment . 

The key is to accumulate full truckloads in the most efficient manner 
possible. This is essential in order that the truck driver can perform in a 
manner that will result in a profitable full-time hauling job. These systems 
are suggested for the above categories: 

1. Containers may be hand-carried to a collection center, but the 
"easiest" system is to hire a collector, municipal or private. To justify 
trucking, all trash and garbage are collected at one time with separation at 
an accumulation point. 

2. Appliances could be "dis-delivered" following the reverse route of 
delivering. The consumer may hire this collection through municipal or pri- 
vate pickup, or he may deliver the products himself to a collection center. 
Appliance dealers may also collect used units as a public service, utilizing 
their delivery system in reverse. A compactor is almost essential at the 
warehouse or collection center so that approximately 200 appliances at 200 
pounds each may be loaded to a truck for transport to the processing plant. 

3. Automobiles may be driven to a car collector, although some require 
a crane truck to take them to a center where full truckloads are accumulated. 
A crusher is probably needed to load a truck with 12 to 14 automobiles, weigh- 
ing 3,000 pounds each. 

The similarities between systems for handling automobiles and appliances 
are greater than those between containers and appliances . This suggests that 
the most effective system for handling appliances will more likely parallel 
that established for autos than that for municipal solid waste. 



118 

The supply of obsolete major household appliances exists on a continuing 
basis in most areas of the United States. Facilities to process appliance 
scrap into a high-quality resource are established in most highly populated 
areas. Markets for appliance scrap do exist in most areas. Legislation and 
regulation are pushing in the direction of resource recovery. The only unful- 
filled requirements that remain are innovative handling systems to effectively 
move the appliance resource back into the existing processing stream. 

References 

1. Institute of Scrap Iron and Steel. Identification of Opportunities for 

Increased Recycling of Ferrous Solid Waste. National Technical Infor- 
mation Service, Springfield, Va., PB-213 577, 1972. 

2. Resource Technology Corporation. An Overview of Discarded Appliances: 

Current Practice Problems/Opportunities. Study prepared for United 
States Steel Corp., November 1977. 



119 



SEPARATION OF NONFERROUS METALS IN AUTOMOBILE SCRAP 
BY MEANS OF PERMANENT MAGNETS 

by 

E. Schloemann 1 



Starting in 1974 the Raytheon Research Division has developed and demon- 
strated simple, economical processes of separating nonmagnetic metals from 
waste material by means of permanent magnets 03-5, 7) . The work was initially 
exclusively aimed at recovering the nonmagnetic metals from shredded municipal 
waste. More recently we have explored the application of the new separation 
methods to the processing of automobile scrap. The present paper describes 
the results of this study. 

The primary economic incentive for the recycling of junk cars is the 
recovery of iron and steel, which make up approximately 80 pet of their 
weight. The value of the steel scrap depends strongly on its purity since 
the presence of other metals such as copper, zinc, and aluminum tends to 
degrade the quality of the steel obtained from the scrap. It is therefore 
highly desirable to separate the different metals as well as possible prior 
to remelting. 

The desire to reclaim uncontaminated steel scrap from junk cars has 
sparked the construction of automobile shredders throughout the world. These 
machines are capable of digesting entire automobiles from which usually only 
the tires, fuel tanks, batteries, and radiators have been removed. The output 
of the automobile shredder consists of a mixture of particles, the largest of 
which are usually about fist size. Light materials, such as fabric, fibers, 
and light plastic, are removed from the mixture by blowing air through the 
shredder and collecting the light materials in an air cyclone. The steel is 
then removed by conventional magnetic separation. 

The nominally nonmagnetic material which remains after magnetic separa- 
tion, the "nonmagnetic shredder outfall," consists of about 33 pet of various 
metals, the remainder being glass, plastic, rubber, rocks, and dirt (2). The 
metals contained in the nonmagnetic shredder outfall are primarily zinc and 
aluminum, with smaller amounts of copper, stainless steel, and iron which 
escaped magnetic separation. Prior to 1970 this material was usually disposed 
of as landfill after a simple handsorting operation to remove the larger 
pieces of nonferrous metal. It has been estimated that only about 28 pet 
of the zinc and aluminum and 14 pet of the copper present in this fraction 
were recovered by handsorting procedures (1) . 

Since 1970 a growing fraction of the nonmagnetic shredder outfall has 
been shipped to central processing plants for extraction of the usable mate- 
rials. Only very few of these plants are currently in operation. In these 

Consulting scientist, Raytheon Research Division, Waltham, Mass. 



120 




NON -METALLIC 
PARTICLES 



METALLIC PARTICLES 
(NON-FERROUS) 



FIGURE 1. - Schematic diagram of the metal separator in 
frontal view (left) and side view (right). The 
shredded trash reaches the separator ramp 
through a chute. Nonmetallic particles con- 
tinue to slide down. Metals are deflected in 
the manner shown in the diagram. 



plants, the nonmagnetic 
shredder outfall is usually 
subjected to two stages of 
heavy-media separation: one 
to remove the metals as a 
group from the lighter mate- 
rials, such as plastic and 
rubber; and a second to 
separate aluminum from the 
heavier metals such as zinc 
and copper. The copper is 
then removed by handsorting. 

Figure 1 is a schematic 
diagram of one of the separa- 
tors used in the present work. 
The operation of this sorter 
is very straightforward. The 
material to be separated 
travels over an inclined 
ramp, 8 feet long and 3 feet 
wide. Permanent magnets, 
which are made of inexpensive 
barium ferrite, are embedded 
into the ramp surface. The 
magnets lie in alternating 
strips of negative and posi- 
tive polarity, each strip 
being oriented at a 45° 
angle to the trash flow. 



As the waste material slides down the ramp through the magnetic field, 
electric eddy currents are generated in the metals. The interaction of these 
electric currents with the magnetic field forces the metals sideways, out of 
the waste stream (3). Nonconductive particles in the feed material — wood, 
plastic, cardboard, and glass — are not affected by the magnetic field, and 
they slide straight down. Thus, the metals and the nonconductive materials 
can be collected in separate bins at the foot of the ramp. 

The simple separator described in figure 1 has the weakness that the sep- 
aration process is seriously interrupted if the particles in the stream are 
strongly attracted by the magnets in the ramp and therefore become attached to 
the ramp surface, thus blocking the path for other particles. Even though 
most of the magnetic particles have been removed from the waste material 
before it reaches the nonferrous metal separator, enough remain to create a 
serious problem unless they are continuously removed. We have, therefore, 
constructed two metal separators which overcome the problem caused by residual 
magnetic particles in the feed stream: (1) The "self-cleaning" ramp metal 
separator (6), and (2) the rotary-drum metal separator (5). 



121 



On the basis of test results it is warranted to draw the following 
conclusions : 

1. Both the ramp-type and the rotary-drum nonferrous metal separator can 
serve useful functions in the processing of automobile scrap. 

2. Although partial segregation of aluminum and zinc can be achieved by 
eddy current separators, positive segregation has not been achieved and does 
not appear possible. Thus the eddy current separation techniques will not 
replace the heavy-media technique. 

3. Eddy current separators installed at the site of automobile shredders 
can beneficiate the nonferrous outfall by removing rubber, plastics, fabric, 
rocks and dirt. Thus only a concentrated nonferrous metal fraction needs to 
be transported to a central processing plant (heavy-media separator) at con- 
siderable savings in transportation cost. 

4. Eddy current separators used after heavy-media separation will 
improve the grade of the aluminum and zinc concentrates . Rocks and glass 
are removed from the aluminum concentrate (light fraction of heavy-media 
plant) and lead and stainless steel from the zinc concentrate (heavy fraction 
of heavy-media plant) . 

References 

1. Chindgren, C. J., K. C. Dean, and L. Peterson. Recovery of Nonferrous 

Metals From Auto Shredder Rejects by Air Classification. BuMines 
TPR-31, 1971, 11 pp. 

2. Dean, K. C, E. G. Valdez, and J. H. Bilbrey, Jr. Recovery of Aluminum 

From Shredded Municipal and Automobile Wastes. Resource Recovery and 
Conservation, v. 1, 1975, pp. 55-66. 

3. Schloemann, E. Separation of Nonmagnetic Metals From Solid Waste by 

Permanent Magnets, I Theory, II Experiments on Circular Disks. 
J. Appl. Phys., v. 46, November 1975, pp. 5012-5029. 

4. . Recovery of Nonmagnetic Metal From Waste. AIP Conf . Proc. No. 32, 

1976, pp. 123-139. 

5. . A Rotary-Drum Metal Separator Using Permanent Magnets. Resource 

Recovery and Conservation, v. 2, 1976, pp. 147-158. 

6. . Self-Cleaning Non-Ferrous Metal Separator. IEEE Trans, on 

Magnetics MAG-13, September 1976, pp. 1496-1498. 

7. Spencer, D. B., and E. Schloemann. Recovery of Non-Ferrous Metals by 

Means of Permanent Magnets. Resource Recovery and Conservation, v. 1, 
1975, pp. 151-165; Waste Age, October 1975, pp. 32-41. 



122 



CHARACTERIZATION OF SCRAP ELECTRONIC EQUIPMENT FOR RESOURCE RECOVERY 

by 
B. W. Dunning, Jr. 1 



Seven million pounds of obsolete military electronic hardware must be 
disposed of each year by the Defense Property Disposal Service (DPDS) of the 
Department of Defense. For example, 12.2 million pounds of electronic units 
were sold in fiscal year 1976 (1_) . Although processing technology is cur- 
rently available, there is no integral system for dry-separating the conglom- 
erate metals of electronic units into salable fractions. Therefore, DPDS has 
been marketing its electronic scrap together with scrap of lesser value, 
classified as irony aluminum. This scrap is sold for 6 to 10 cents per pound, 
although its true value may be considerably higher. 

To better estimate the value of such electronic scrap, the Bureau of 
Mines, as part of its secondary resource recovery activity and under a cooper- 
ative agreement with DPDS, is assembling a continuous process experimental 
unit (PEU) that involves a series of dry-separation techniques. The process 
includes shredding, followed by wire picking, air classification, screening, 
magnetic, electrostatic, and eddy current separation methods. Additional 
treatments may be added to upgrade some of the metal fractions. The ultimate 
goal of this PEU is to obtain clean fractions of magnetic metals, aluminum 
alloys, copper alloys, nonmagnetic austenitic stainless steel, and nonmetals 
from shredded electronic scrap in order to assess its marketable value. 

In a characterization study conducted for DPDS of a sample lot containing 
36 separate electronic components available for scrap recovery, using current 
scrap values for base and precious metals, an estimated average value of $0.22 
per pound was calculated. It was apparent that the 36-unit sample described 
in this study consisted of pre-1957 electronic black boxes and was not repre- 
sentative of higher value scrap that would be obtained from more recent 
electronic equipment. 

Because of the variability in composition of electronic scrap, DPDS needs 
an efficient and reliable method of assessing its value. Current Bureau of 
Mines research involves the construction of a continuous PEU which will demon- 
strate the feasibility of mechanically separating electronic scrap into mar- 
ketable fractions. When completed, this PEU will provide a direct and rapid 
means of accurately assessing the value of such electronic scrap. 

Reference 

1. General Accounting Office. Additional Precious Metals Can Be Recovered. 
Dec. 28, 1977, 37 pp. 



Metallurgist, Avondale Metallurgy Research Center, Bureau of Mines, 
Avondale, Md. 



123 



PROGRESS IN RESOURCE RECOVERY IN APPLIANCE MANUFACTURING 

by 
T. H. Goodgame 1 and E. W. Hartung 2 



Industrial solid waste management has been discussed a great deal, usually 
from the basis of what further can be done to recover useful materials and 
energy and to decrease the quantities for which final disposal as waste is 
required. 

One substantial study which has been done is that of Sobas, Vachon, and 
Goodgame (1), presented at the Detroit (1973) meeting of AIChE. At this time, 
it was shown that about 90 pet of the potential solid waste generated by the 
facility under study was already being recovered for reuse in the plant, or 
was being segregated and sold for recycle through the secondary materials 
industry. 

Sobas' work indicated that the problem was essentially economic, and that 
the further reduction would only be achieved by changes in economic effects of 
taxes, regulations, energy cost, etc. 

Table 1 shows the results that Sobas reported. Since that time, addi- 
tional improvements in resource reduction and recovery have been made, ash 
shown in table 2. Recovery of potential solid wastes generated has been 
increased from about 87 pet in 1973 to 93 pet in 1977, equivalent to a reduc- 
tion of 46 pet in solid wastes not recovered in 4 years. 

What changes in operation would make recycling more profitable to the 
operator? Probably the largest single item would have been the ability, and 
willingness, to store the more valuable metals (copper, zinc, aluminum) until 
sufficient quantities were in inventory to obtain a good price from the scrap 
dealer. The same thing applies to motors, wires, coils, and stainless steel. 
Income from these items would have been increased 50 pet to 100 pet by this 
simple procedure. 

Table 3 presents the income increase that would have resulted to the 
operator of a project if the sales price of the recovered materials had been 
the same as Whirlpool's St. Paul division was receiving for its scrap metal at 
that time. The increased income for the 22-month period is $5,456, or approxi- 
mately $250 per month. This, added to the original net income, would make a 
monthly income of about $475. This is equivalent to a weekly salary of $220 
for 40 hours per week, or an hourly rate of $5.50 per hour. This is certainly 
a comparable wage for many industrial jobs at that time. 



director, whirlpool Corp., R&E Center, Benton Harbor, Mich. 
2 Facility engineer, Whirlpool Corp., St. Paul Div., St. Paul, Minn. 



124 



TABLE 1. - Solid waste — 1973 data, pounds per day 



Item 



Steel, 



Plastics 

Corrugated paper, etc 

Containers : 

Pallets (nonreturnable) 

Drums (nonreturnable) 

Lube and hydraulic oils, drawing compounds.. 

Paints , thinners , phosphate scale 

Processing solids: 

Wastewater treatment plant 

Strip salts and paint 

Floor sweepings, cafeteria and office wastes 

Scrap purchased parts 

Total . , 



Potential 



87,020 

1,920 
12,000 

3,990 

209 

1,200 

1,056 

9,600 

1,320 

2,400 

100 



120,815 



Actual 



Small (inc. in 
floor sweepings) 
10 
300 

50 

133 

1,200 

1,056 

9,600 

1,320 

2,400 

100 



116,169 



^S.4 pet solid waste not recovered. 



TABLE 2. - Solid waste — 1977 data, pounds per day 



Item 



Potential 


Actual 


87,020 


Small (inc . in 




floor sweepings) 


1,920 


10 


12,000 


300 


3,990 


50 


209 


133 


1,200 


400 


1,056 


1,056 


9,600 


3,000 


1,320 


1,320 


2,400 


2,400 


100 


100 


120,815 


18,679 



Steel, 



Plastics , 

Corrugated paper , etc , 

Containers : 

Pallets (nonreturnable) 

Drums (nonreturnable) *...., 

Lube and hydraulic oils, drawing compounds., 

Paints , thinners , phosphate scale , 

Processing solids: 

Wastewater treatment plant , 

Strip salts and paint , 

Floor sweepings, cafeteria and office waste, 

Scrap purchased parts , 

Total 



7.2 pet solid waste not recovered. 

While it was not taken into consideration in the development of this 
data, there would also have been decreased expenses involved in less frequent 
trips to the scrap dealer. 

Income could also have been increased by putting somewhat more effort 
into the disposal of collected fasteners to small repair shops, garages, and 
home handymen. This is not a large item, but could have provided a very good 
return for the effort involved. 



125 



TABLE 3. - Metals produced, pounds 



Price 






differential 


Quantity, 


Increased 


by volume 


pounds 


income 


disposal, 






cents per lb 






1 


358,860 


$3,588.60 


2 


31,540 


315.40 


1 


18,620 


186.20 


7 


1,251 


87.57 


11 


1,484 


163.24 


20 


1,552 


310.40 


No change 


- 


- 


No change 


- 


- 


10 


6,509 


650.90 


2H> 


3,694 


92.35 


1 


5,106 


51.06 


- 


- 


$5,445.72 



Coated steel , 

Uncoated steel , 

Cast iron , 

Stainless steel 

Copper , 

Brass 

Unburnt wire 

Coils, copper, and aluminum, 

Aluminum 

Zinc die cast 

Motors 

Total , 



Finally, what can the appliance industry do? The most obvious thing is 
to make appliances easier to take apart. Motors are a problem — could these 
be put in the units so that a blow from a sledge hammer, or simply loosening 
two bolts, would permit their easy removal? Could wiring harnesses be made 
easier to remove? Could motors be built so that the aluminum or copper in 
the winding could be removed more easily? There has been thought and effort 
in this direction, but progress has been slow because of the increased costs 
to the consumer. Consideration could also be given to reducing the number of 
different materials that go into any appliance. For example, if the motor is 
aluminum could the wiring and coil also be aluminum, and thus use no copper 
at all? 

Reference 



1. Sobas, W., L. Vachon, and T. Goodgame. Industrial Solid Waste Management, 
Pres. at the 75th National Meeting, AIChE, Detroit, Mich., June 4, 1973, 



126 



RECOVERY OF CADMIUM FROM NICKEL-CADMIUM SCRAP BATTERIES 

by 
D. A. Wilson 1 



The manufacture and use of nickel-cadmium alkaline batteries began to 
grow in the late 1950' s. During the period from 1966 to 1971, approximately 
3 pet of the U.S. primary cadmium demand was consumed by battery manufac- 
turers (4). From 1971 to 1975, the demand grew from 3 pet to 13 pet. It 
was estimated by the battery manufacturers (1) that by 1981 2.2 million 
pounds, or greater than 20 pet of the yearly U.S. demand for cadmium, will 
be consumed by battery manufacturers. The United States is dependent on 
Canada, Mexico, and Australia for greater than 60 pet of its primary cadmium 
supply. 

At present, there is no commercial process being used in the United States 
to recover the total metal values from Ni-Cd battery scrap. Virtually all of 
the scrap recovered is shipped overseas, where it is processed and returned 
to this country as refined metals. Several scrap dealers are breaking the 
battery cells and hand-separating the positive and negative plates . The 
positive plates, containing 1 to 2 pet cadmium, are smelted in the United 
States to a high-ferro nickel alloy. The cadmium-rich negative plates are 
shipped overseas. 

As part of its efforts in secondary metals recovery, the Bureau of Mines, 
U.S. Department of the Interior, pursued this research, which has led to the 
development of a pyrometallurgical method for recovering metallic cadmium and 
a nickel-iron residue low in cadmium (fig. 1). This paper is a progress 
report of the laboratory tests that have been conducted to date. Work is 
continuing on scaling up the method to test 10- to 20-pound charges of battery 
scrap. At the time of this investigation, there were only three other known 
methods: A hydrometallurgical method developed in 1971 by the Bureau of 
Mines (5) , a sulfuric acid leach and electrolytic recovery method (2) , and 
a pyrometallurgical method based on a French patent that f ave no details (3) . 



Electric resistance furnace 




Pressure relief hole 



Thermocouple 
Electric heating tape 



Nl-Cd battery paste 



FIGURE 1, 



Schematic of retort-condenser 
system. 



This research has progressed to 
larger scale testing of 10- to 20- 
pound charges of Ni-Cd battery scrap. 
The small laboratory tests have suc- 
cessfully demonstrated that the cad- 
mium in the residue can be consistently 
reduced to 0.05 pet or less by oper- 
ating at 900° C and atmospheric 
pressure for 2 hours using 2.5 pet 
carbon. Although the initial 

Research chemist, Avondale Metallurgy 
Research Center, Bureau of Mines, 
Avondale, Md. 



127 



large-scale test did not reduce the cadmium to less than 0.1 pet, no difficul- 
ties are anticipated in achieving this level and producing a cadmium conden- 
sate with low impurities. Work will be continued on the large-scale retort. 

References 

1. Chizhikov, D. M. Cadmium. Pergamon Press, New York, 1966, 258 pp. 

2. Knapp, J. R., Jr. Electrolytic Process of Recovering Nickel and Cadmium 

From Spent Battery Plates. U.S. Pat. 3,506,550, April 1970. 

3. Kupferhuette, D. Recovery of Nickel and Cadmium From Battery Scrap. 

French Pat. 1,577,619, August 1969. 

4. U.S. Bureau of Mines. Minerals in the U.S. Economy (1966-75): Ten-Year 

Supply-Demand Profiles for Mineral and Fuel Commodities. 1976, 99 pp. 
(Cadmium, p. 17) . 

5. Wilson, D. A., and B. J. Wiegard, Jr. Recovery of Nickel and Cadmium 

From Scrap Batteries. BuMines RI 7566, 1971, 15 pp. 



128 



MISCELLANEOUS 

CONGRESSIONAL AND AGENCY ROLES IN RESOURCE RECOVERY 

by 
F. McManus 1 



The conventional wisdom in Washington is that the Congress always reacts 
to problems and is last to act. Sometimes that is true, but in the case for 
processing wastes for energy and materials, Congress has clearly been the prod 
behind the Federal agencies. Lest we get too euphoric, I suspect that this 
phenomenon exists because it is one of the few environmental issues that no 
one is opposed to . 

As you know, Congress passed the Solid Waste Disposal Act in 1965, which 
gave rise later to some original work by the Bureau of Solid Waste Management 
in the Department of Health, Education, and Welfare. Dick Vaughan, our next 
speaker, was the director of that distinguished Bureau, then in the Public 
Health Services. Earlier, the Bureau of Mines had been quite active in 
resource recovery, as evidenced by this series of symposia begun in 1968 
and its work in College Park and elsewhere. 

Nevertheless, it was the then Senate Public Works Committee which in 1969 
and 1970 took the leadership and passed the Resource Recovery Act. It was 
also during 1970 that President Nixon created EPA and a group of industry and 
labor leaders founded the National Center for Resource Recovery. Since that 
time, a great deal of resource recovery progress has taken place, but the 
Federal role has been much less than the public had eagerly anticipated. The 
principal culprit is almost universally agreed to be the Office of Management 
and Budget (0MB). Most seem to agree that 0MB analysts, who fear a massive 
multi-billion-dollar waste-water- type program, are the real villains. I don't 
agree with that assessment, but that is another subject. 

Senator Randolph has sustained an interest in the Resource Recovery Act 
and its implementation. He held a number of hearings as chairman of the 
powerful Public Works Committee and as chairman of a special panel after he 
relinquished the chair of the cognizant subcommittee. When Senator Randolph's 
renamed Environment and Public Works Committee finished work on its bill in 
May 1976, no one thought the House would or could pass a similar bill. 

A new House subcommittee surprised everybody by acting on a bill intro- 
duced by its chairman, Fred Rooney. He and his Subcommittee on Transportation 
and Commerce staff drafted a new bill, introduced it in June, and held hear- 
ings almost immediately. Soon thereafter, the subcommittee and full committee 
passed the bill. Keep in mind that both the Democrats and Republicans were 
holding their national conventions during that summer and some members of 
Congress took vacations . 

Editor and publisher, Resource Recovery Report, Washington, D.C. 



129 



Among the major changes which the House Committee made were new duties 
for the Department of Commerce to "encourage greater commercialization of 
proven resource recovery technology." The subcommittee felt that EPA neither 
should nor could attempt to regulate as well as promote resource recovery. 
It was also clear that the members felt there was an important role for the 
Federal Government in advancing resource recovery and that EPA was not carry- 
ing out this role. In the space of 3 weeks the House passed its bill, and 
staffs of both House and Senate Committees worked long hours to reconcile 
differences so that the Senate and House each agreed on a bill which President 
Ford signed on October 21, 1976. 

One major deficiency of the law is the failure to provide a specific role 
for the Department of the Interior. Ironically, many members of Congress and 
many more Congressional staff had visited the two prototype waste recovery 
systems which the Bureau of Mines has been operating near College Park, Md., 
just 10 miles from Capitol Hill. 

I describe the genesis of the law to give you a notion of how strongly 
the Congress feels about resource recovery. Now lest you think the Congres- 
sional progenitors went to other things, they didn't! Within 6 months 
Congressman Rooney held oversight hearings. In 1978 Mr. Rooney held an addi- 
tional 3 days of oversight hearings, and Senator Randolph has also scheduled 
3 days of oversight hearings. Moreover Congressman Brown, chairman of the 
Environmental and Atmosphere Subcommittee, has scheduled oversight hearings 
on the research, development, and demonstration portions of the law. Over- 
sight hearings on new legislation are not common. I hope you agree that 
inadequate Federal agency action in resource recovery does not reflect the 
views of Congress. One final manifestation of congressional interest has been 
the work of two congressional agencies, the General Accounting Office (GAO) 
and the Office of Technology Assessment (OTA) . 

GAO, Congress' investigatory agency, has undertaken several solid waste- 
resource recovery studies during the past several years. Two are underway 
now. One is a comprehensive assessment of bioconversion developments, and 
the other describes and evaluates various resource recovery systems for muni- 
cipal solid wastes in four categories: Those which are operating, under 
construction, in advanced planning, and in some stage of feasibility study. 
GAO's posture has been that of an advocate for resource recovery. 

In the meantime the Office of Technology Assessment is about to release 
a comprehensive analysis of "resource recovery, recycling and reuse of mate- 
rials from municipal waste." The study has been underway for more than 
2 years and has generated a great deal of expectation and controversy. It 
assesses transportation rates, tax policy, product disposal charges, the 
beverage container issue, and incentives and disincentives for recycling. 



130 



ASTM COMMITTEE E-38 ON RESOURCE RECOVERY 

by 
R. D. Vaughn 1 



The concept of recovering material and/or energy from solid waste and 
reusing these materials as a national resource has been with us for some time 
now and, as a concept, has joined the ranks of motherhood and the American 
flag as the thing to do. Since its inception in 1968 this symposium has 
stressed reuse of waste products from the mineral industry. Federal solid 
waste legislation, enacted first in 1966 and amended several times since, has 
always contained references to resource recovery as a desirable concept, and 
the latest version is even titled the Resource Recovery and Conservation Act 
of 1976. The real problem is significant implementation of this desirable 
concept in existing governmental and industrial institutions. 

What has prevented this? In the "early" days following enactment of the 
original Federal solid waste legislation, there was much talk of developing 
technology to make possible utilization of resource recovery from solid waste 
otherwise destined to find its way through the Nation's waste streams into 
some treatment and disposal site such as an incinerator, sanitary landfill, 
or regretfully too often an open dump. A flurry of activity followed, par- 
tially supported by Federal financing, which generally concluded — we have the 
technology to separate desired materials from waste streams. We also have the 
technology to convert it to a desired product, although in some cases the cost 
might be excessive in the competitive marketplace and the dependability eco- 
nomically unsatisfactory. Technology has been demonstrated (3-4) throughout 
the United States, but still there has been no major move to reuse waste prod- 
ucts rather than rely on disposal. 

It was then found that economic markets do not exist for the vast mate- 
rial capable of being recovered and reused. Unless someone uses the material, 
it does little good to separate it merely to create another solid waste accu- 
mulation (at considerable cost) which still requires disposal. In some cases, 
resource recovery processing costs were so high that recovered material could 
not economically compete with virgin material. In other cases, the overall 
need for such material does not exist . Concern for conservation of energy has 
helped solve the first problem, and at least we have a little better handle on 
the second to help interested parties provide recovered material and energy to 
U.S. industry. Many parties trying to encourage industry to use recovered 
materials learned that even when the recovered products from waste are competi- 
tive with virgin materials, some industries are reluctant to use them because 
they do not know how they will perform and have no standards or specifications 
to serve as the basis for rejection or acceptance of a product, whether it be 
raw, intermediate, or finished. As Dr. Harvey Alter has pointed out (1 ) , the 

Director, Environmental Affairs and Quality Assurance, ITT Community 
Development Corp., Palm Coast, Fla. 



131 



secondary materials industry has employed specification for recycling products 
for over half a century but generally has been concerned with utilization of 
scrap from industrial operations rather than recovery of material from mixed 
municipal waste otherwise destined for disposal. Many feel different forms of 
specifications must be developed both to encourage recovery and reuse of these 
materials and to afford the user assurance that he will be receiving a quality 
product satisfactory to his needs. It was to meet this need that ASTM Commit- 
tee E-38 on Resource Recovery was established in 1974. 

The American Society for Testing and Materials is a management system for 
the development of voluntary full-consensus standards (2) . ASTM standards are 
formulated by balanced committees with distinct biases according to their 
interest. The committees are comprised of designated balances of users and 
producers as well as general interest groups concerned with the particular 
standard being promulgated. ASTM standards are not company standards, indus- 
try standards, professional standards, or government standards, although all 
these have their place and are considered in ASTM full-consensus standards. 
Also representatives of industry, government, educational, and public interest 
groups participate together in the development of ASTM full-consensus stand- 
ards. The society's work is carried out by approximately 130 standards com- 
mittees working in such diverse areas as surgical implants, plastic pipe, 
textiles, and forensic science. One of these committees is ASTM Committee 
E-38 on Resource Recovery. The scope of this committee is "The development 
of methods of test, specifications, recommended practices, and nomenclature; 
the promotion of knowledge, and stimulation of research relating to material 
and energy resources, recoverable, or potentially recoverable from waste. 
The waste for resource recovery is here defined as that portion of waste 
which is collected from industrial, commercial, or household sources destined 
for disposal facilities. The committee will coordinate its efforts working 
in this and related fields . " 

References 



1. Alter, H. Development of Specifications for Recycled Products. National 

Center for Resource Recovery , Inc . , 1978, 8 pp. 

2. American Society for Testing and Materials. Questions Most Frequently 

Asked About ASTM. Philadelphia, Pa., 1975, 7 pp. 

3. National Center for Resource Recovery, Inc. Materials Recovery System. 

Engineering Feasibility Study. 1972, 350 pp. 

4. . New Orleans Resource Recovery Facility. Implementation Study. 

1977, 427 pp. 



132 



AN APPROACH TO ENERGY ATTENUATION OF EXPLOSIVE WASTES 
IN PROCESSING EQUIPMENT 

by 

A. R. Nollet, 1 E. T. Sherwin, 2 and A. W. Madora 3 



The solid waste resource recovery industry has been growing rapidly in 
the past decade — spurred by a perceived shortage of raw materials and energy. 
All existing resource recovery plants that are known to the authors currently 
employ one of three initial processing steps: 

1. Mass burning in incinerators. 

2. Wet pulping. 

3. Dry shredding. 

By far the greatest number of resource recovery plants employ dry 
shredding as the first processing step. 

The use of shredders to process solid waste has increased remarkably in 
the past 5 years. According to the recent Waste Age Survey (1) of shredding 
operations in the United States and Canada, the number of reported refuse 
shredding installations has multiplied approximately fivefold, from 27 
shredding plants reported in 1971 to approximately 144 in 1976. Many of 
these installations shred prior to landfilling, primarily because the Environ- 
mental Protection Agency considers that landfilling of shredded refuse can be 
an environmentally acceptable disposal method that reduces the need for daily 
soil cover and increases site life. There are several other installations, 
with numerous others in the planning stage, that shred as a first step in ' 
order to obtain a relatively homogeneous waste stream said to be more amenable 
to automated material handling and other processes associated with resource 
recovery, incineration, or the preparation of refuse-derived fuels. 

Unfortunately, the increased use of shredders for processing solid waste 
has resulted m frequent explosions within the shredders and adjacent process- 
ing equipment causing great concern for the safety of equipment and personnel. 
Municipal solid waste is a heterogeneous mixture over which the solid waste 
processor has little or no control-one may expect daily the delivery of poten- 
tially explosive materials such as cans of solvent, cans of gasoline, combusti- 
ble dust and commercial or military ordnance. Such materials are readily 
ignited by sparks from the hammers in the shredder striking metal, or by 
localized temperature buildup within the shredder. 



president, AENCO, Inc., subsidiary of Cargill Inc., New Castle, Del. 

Vice president AENCO, Inc., subsidiary of Cargill, Inc., New Castle, Del. 
Director of Public Works, New Castle County, New Castle, Del. 



133 



The Factory Mutal Research Corp. recently conducted an assessment on a 
nationwide basis of the hazards of explosions from the shredding of municipal 
solid waste for the U.S. Energy Research and Development Administration (3). 
The summary of this survey indicates the following explosion experience in 
solid waste resource recovery plants as of the end of 1975: 

Total tons processed 8,295,000 

Total explosions 97 

Explosions causing significant damage 69 

This experience represents a frequency of explosions of one for every 85,000 
tons shredded; thus, a typical plant processing 1,000 tons per day of munici- 
pal solid waste may expect an explosion every 3 months . Fortunately there 
were serious personnel injuries in only three of the explosions, and even more 
fortunately, there had been no fatalities to the date of the survey. We are 
sorry to report that both serious injuries and fatalities have occurred during 
shredder explosions in the past 2 years. 

One of the explosion protection measures described in the Factory Mutual 
Report (3) and the subsequent paper by Zalosh (2) is the use of a fine water 
spray (microf og) in the shredder . A rigorous design basis for a water spray 
system is lacking, but the basic concept is to use the water mist to quench 
an incipient gas, vapor, or dust explosion before devastating pressures are 
developed. In terms of an energy balance, the water mist should dissipate 
the rate of heat generated by combustion in order to prevent continued flame 
propagation through the combustible gas, vapor, or dust. Since more water 
droplets promote the rate of heat absorption, an effective water-spray system 
should consist of small, closely spaced droplets. 

The following are conclusions regarding the success of this installation: 

It is certain that the microfog system will not significantly attenuate 
explosions resulting from substances that contain their own oxidant, such as 
dynamite, military ordnance, and smokeless powder. 

It is believed that the microfog system has probably attenuated the 
forces that are usually experienced during a vapor or dust explosion. It 
is believed that some of the recent explosions would have caused severe damage 
had not the microfog system been installed. Plant workers feel more secure 
with the microfog system installed. 

Further testing and operational experience are necessary to define better 
design criteria than those that we have presented. 

It is no longer believed that dry shredding should be the first process- 
ing step in new plants. 

It is recommended, at a minimum, that existing shredding plants be retro- 
fitted with (1) a well-designed explosion-venting system to allow most of the 
explosive gases to vent to the atmosphere out of the plant, and (2) some 
variant of the microfog spraying system. 



134 



It is suggested that, in all cases where funds are available, considera- 
tion should be given to supplementing the foregoing installations with an 
explosion detection and suppression device utilizing the halogenated hydro- 
carbons as the suppressant — extreme care must be taken in the design, location, 
and method of keeping unplugged the detector tubes . 

References 

1. Waste Age Magazine. Solid Waste Shredding: Continued Growth in Waste 

Processing. Industry Survey, July 1976. (Revised November 1977 by 
Shredder Sub -Commit tee, Waste Equipment Mf rs . Institute.) 

2. Zalosh, R. G. Factory Mutual Research Corporation — Explosion Protection 

in Refuse Shredding. Pres. at the 5th Nat. Cong, on Waste Management 
Technology and Resource and Energy Recovery, Dallas, Tex., Dec. 7-9, 
1976. 



3. Zalosh, R. C, S. A. Wiener, and J. L. Buckley. Assessment of Explosion 
Hazards in Refuse Shredders. Prepared for the U.S. Energy Research 
and Development Administration under Contract No. E (49-1) -3737, 
April 1976, 190 pp. 



135 



DEVELOPMENT OF CONTINGENCY PLAN STANDARDS FOR ACCIDENTS 
WITH HAZARDOUS WASTE MATERIALS 

by 

P. C. Knowles 1 and R. C. Tucker 2 

Under the Resource Conservation and Recovery Act of 1976 (Public Law 
94-580) enacted by the Congress of the United States, the United States 
Environmental Protection Agency (EPA) is required to promulgate regulations 
with regard to the treatment, storage, and disposal of hazardous wastes. 

The act is comprised of eight subtitles which are being addressed, at 
the request of the EPA, by consultants with broad backgrounds and expertise 
in these fields. At the present time, rules and regulations are in various 
degrees of completion. Draft regulations should be out in the very near 
future. 

In particular, Subtitle C, entitled "Hazardous Waste Management," 
addresses the following sections: 

3001 Identification and listing of hazardous wastes 

3002 Standards applicable to generators of hazardous wastes 

3003 Standards applicable to transporters of hazardous wastes 

3004 Standards applicable to owners and operators of hazardous waste 
treatment, storage and disposal facilities 

3005 Permits for treatment, storage or disposal of hazardous waste 

3006 Authorized State hazardous waste program 

3007 Inspections 

3008 Federal enforcement 

3009 Retention of State authority 

3010 Effective date 

3011 Authorization of assistance to States 

The purpose of the study was to examine a number of management issues 
pertinent to Section 3004 (1) and (2) of the Resource Conservation and Recov- 
ery Action of 1976. The study was divided into four tasks, covering 



Partner, Dames & Moore, Boca Raton, Fla. 
2 Associate, Dames & Moore, Washington, D.C. 



136 



1. Financial responsibility of hazardous waste management firms, 

2. Continuity of operations at hazardous waste sites, 

3. Contingency plan standards for accidents at hazardous waste facili- 
ties, and 

4. Training and certification for hazardous waste management employees. 

The various types of hazardous waste disposal facilities, treatment 
methods, or combinations presently being used include but are not necessarily 
limited to the following: 



Facilities 



1 . Landfills . 

2 . Incinerators . 

3. Waste lagoons or ponds. 

4. Land burial at depth. 

5. Deep well injection. 

6. Near-surface land burial. 



Final Treatment Processes 



1. Oxidation/reduction. 

2. Neutralization. 

3. Chemical degradation. 

4. Detoxification. 

5. Open burning/ detonation. 

6 . Hydrolysis . 

7. Biological degradation. 

8. Resource recovery. 

Preparatory Treatment Processes 

1. Flocculation, sedimentation, and filtration. 

2. Precipitation. 

3. Ammonia stripping. 

4. Evaporation. 

5. Centrifugation. 

6. Carbon sorption. 

7. Solidification and/or fixation. 

8. Solvent extraction. 

9. Vacuum distillation. 



Once the contingency plan standards were developed, five regulatory 
strategies relating to the approach, scope, and stringency of the standards 
were evaluated. These strategies were 



137 

1. Standard by facility versus uniform standards for all facilities. 

2. Federal regulation versus State regulation. 

3. Exact and specific requirements versus ad hox flexible requirements. 

4. Handling volume limitation. 

Under Section 3004 specifications, the design of the facility must also 
be undertaken with a goal of reducing hazards of material dispersion to the 
environment. This further reduces the consideration of contingency plan costs, 
in that protective structures such as dikes, sumps, paving to reduce inflow of 
spills into ground waters, etc., must be considered regular facility costs, 
rather than "emergency devices." The facility costs for contingency actions 
are those for 

1. Fire control and suppression systems. 

2. Employee protective equipment donned during emergency periods (as 
contrasted to protective equipment worn during material unloading 
or handling) . 

3 . Emergency communication equipment . 

4. Assessment model costs. 

5. Neutralizing, sorbing, or barrier materials used after or during 
spills. 

6. Contingency response costs. 

7. Facility diseconomies resulting from contingency considerations, such 
as inventory limitations. 

8. Governmental emergency services for fire, medical, and police actions. 

9. Other direct costs for contingency action or protection such as 
security service during nonoperating hours, standby equipment, 
standby storage, and demurrage. 

Although it is beyond the scope of this paper to list all of the contin- 
gency plan standards, evaluations of the three sets indicates the effects and 
stringency of the facility operation. 

Set No. 1 — This set of contingency plan standards contains a minimal num- 
ber of requirements. As such, it closely resembles regulations in effect or 
under consideration in several States. The effectiveness of this type of 
regulatory approach relies primarily on the competence of the permit-granting 
authority in evaluating the effectiveness of proposed plans. The most impor- 
tant advantage in this type of regulation is its ability to cover a wide range 
of facility types and size. In addition, administrative costs are kept at a 



138 

minimum. The major disadvantage of the approach is the lack of guidance pro- 
vided to the facility operators in preparing contingency plans. 

Set No. 2 — The standards in this set are markedly more specific and 
stringent than those presented in set No. 1, and as such would more effectively 
insure protection of human safety and the environment. An additional advantage 
of specific contingency plan requirements is the relative ease of determining 
compliance of submitted plans with the regulations. Associated with these 
more stringent requirements would be increased costs for implementing the con- 
tingency plan. The major disadvantage of this regulatory approach is a lack 
of flexibility. Unless provisions were made to enable the granting of vari- 
ances to certain facilities from full compliance with the regulations, the 
requirements might prove to be excessive for some facilities, particularly the 
smaller operations. Such possible overregulation presents the threat of suits 
claiming that the regulations are "arbitrary and capricious." 

Set No. 3 — This set represents a thorough treatment of requirements to 
insure optimum protection of human safety and the environment from accidents 
occurring at facilities employing land burial or lagooning. A combination of 
specific and flexible requirements are included in the set. As with the 
standards presented in set No. 2, some provision must be made to enable grant- 
ing of variances to certain facilities deemed exempt from certain requirements. 
Again, the inclusion of specific standards facilitates the review of contin- 
gency plans by the permit -granting authority. 

The three standard sets as well as other variations presently are being 
reviewed by the EPA. The legal power to promulgate these contingency stand- 
ards and their degree of stringency rests in the hands of the EPA. Regardless 
of the contingency plan standards enacted into law, virtually the entire haz- 
ardous waste industry, including the chemical industry, manufacturing industry, 
and mining industry, will be affected in some fashion by Public Law 94-580. 
These management decisions concerning hazardous waste disposal are a step in 
the direction of insuring that adequate programs are implemented to safeguard 
all those people involved in the hazardous waste industry, as well as the 
public, from any type of accidental release of hazardous wastes to the environ- 
ment. Hopefully, the resultant EPA rules and regulations will aid the mining 
industry in developing uniform and effective programs for the collection and 
containment of hazardous waste materials . 

References 

1. Booz-Allen Applied Research, Inc. A Study of Hazardous Waste Materials, 

Hazardous Effects and Disposal Methods. U.S. Environmental Protection 
Agency, EPA-670/2-73-14, 1973, 3 volumes. 

2. Braunstein, Jr. (ed) . Underground Waste Management and Artificial 

Recharge. The American Association of Petroleum Geologists, Inc., 
v. 2, 1973. 






139 



UTILIZING WASTES AND BYPRODUCTS IN CANADIAN CONSTRUCTION 

by 
J. J. Emery 1 



The spurt of materials conservation activity triggered by the 1973-74 
fourfold rise in petroleum prices has been followed by steady progress as 
the close interaction of energy, materials and environment was recognized 
and measures were adopted to insure long-term supplies of the Earth's non- 
renewable resources. However, current consumption and waste generation 
statistics still indicate a wide scope for applying a range of conservation 
measures such as more efficient use of energy and materials, decreased growth 
in demand, slowing of demographic expansion, development of new materials and 
manufacturing processes, and recovery and recycling of more wastes and 
byproducts (l_-2^ 4.-5) • It is the purpose of this paper to outline the 
positive contribution that waste and byproduct utilization in construction 
makes to materials conservation within the context of current Canadian prac- 
tice, and to indicate potential trends. 

The Canadian construction industry, as a major force in a developing 
country with long transportation distances and rapid urbanization, requires 
large per capita supplies of low-unit-cost industrial minerals (mainly 
aggregates) that are becoming depleted near some urban demand points, or 
alienated by sprawl ( 3) . Coupled with bulk material requirements, the demand 
for cementing agents (mainly asphalts and portland cements) and fuels that 
are becoming increasingly expensive remains firm. These materials and 
indirect energy considerations also involve a growing concern for environ- 
mental protection during all construction-related activity, particularly 
minerals extraction and thermal processes. At the san i time, waste handling 
and disposal pose a severe problem, given the current emphasis on improved 
plant conditions and environmental impact. For activities in urban areas, 
the total cost of disposal to approved sites ranges from about $5 to $15 
per ton, a cost factor of concern as profit margins on primary products are 
under pressure. Further, local authorities are tending to limit the dumping 
of nonmunicipal wastes in landfill sites, and requiring major plants to 
develop their own disposal areas that must meet stringent environmental 
controls . 

Given this background, waste and byproduct utilization is particularly 
attractive since it couples resource conservation with attenuation of dis- 
posal problems. While numerous research studies, demonstration projects, 
and current applications have resulted in optimistic projections of the role 
of wastes and byproducts as materials, some caution is required in the 
Canadian context as there are several limiting factors to be faced: Current 

Associate professor, Department of Civil Engineering and Engineering 
Mechanics, Construction Materials Laboratory, McMaster University, 
Hamilton, Ontario, Canada. 



140 

economic conditions, agency conservatism, obsolete specifications, and indus- 
try structures often result in little demand for a waste or byproduct that 
shows potential; mineral wastes that could make the largest contribution to 
bulk material requirements are widely distributed and usually remote from 
demand points; and the inherent variability of many wastes and byproducts. 
It is considered that the impact of waste and byproduct utilization on growing 
bulk materials needs will continue to be small, and the significant contribu- 
tion will be in terms of recoverable and replaceable energy and special appli- 
cations. These concepts will be illustrated by outlining applications for 
pelletized blast furnace slag, surplus sulfur, and steel slag, as shown in 
the inventory of Canadian wastes and byproducts of major interest as construc- 
tion materials. 

There is still much potential for the utilization of wastes and byprod- 
ucts as resources to be developed, and the inventories are certainly avail- 
able. However, optimistic forecasts must be tempered with the harsh reality 
of both technical and economic constraints that will tend to limit applica- 
tions to those where energy is recovered or saved, or the waste or byproduct 
offers performance advantages. An integrated approach by governmental, 
industrial, and research organizations, taking into account the technical, 
economic, environmental, and energy factors involved, is needed to foster the 
new technology required for waste and byproduct management and utilization. 



141 

INVENTORY OF CANADIAN WASTES AND BYPRODUCTS OF MAJOR INTEREST 
AS CONSTRUCTION MATERIALS 

(See notes at end of the inventory) 

WASTE /BYPRODUCT PRODUCTION MAIN USES 

1. Blast furnace slags 2.2 x 10 6 metric tons/yr Air cooled — aggregate (base 

(air cooled and PCC, AC), ballast, EF, 

pelletized) mineral wool 

Pelletized — lightweight aggre- 
gate (PCC, masonry), sepa- 
rately ground slag cement 

23 pet of 1975 pig iron production. Production fairly static. Pelletizing develop- 
ing rapidly (-0.2 x 10 6 metric tons in 1976), remainder air cooled. Hamilton 
(Southern Ontario) major production and utilization area. Use as aggregate covered 
by ASTM and CSA standards. Separately ground slag cement is covered by CSA A363. 
Research in progress: partially preground pelletized slag in autoclaved masonry 
production 1 and pelletized slag in base stabilization. 1 Most of available blast 
furnace slag utilized. Full utilization anticipated in near future. 

2. Sulfur 16 x 10 6 metric tons sur- Insulations, 1 AC, concretes, 

_plus_currently in storage coatings 1 

Sulphur Development Institute of Canada (SUDIC) estimate for end of 1975, projection 
of up to 25 x 10 6 metric tons by 1980. Only surplus byproduct sulfur is considered 
in context of this paper, mainly from Alberta sour gas fields. Standards for vari- 
ous uses not developed yet. Significant research and development in progress: 
insulation 1 (sulfur foam and thermal AC) , AC (binder system, sulfur/asphalt emul- 
sions, and specialty applications), concrete (hot poured sulfur concrete, additive' 
to PCC, 1 and impregnating agent for PCC), and coatings 1 (mortarless construction, 
linings, and soil stabilization). Little surplus sulfur now utilized in construc- 
tion as mainly at developmental stages. More utilization should develop, including 
international exchange of technology. 

3. Fly ash 1.8 x 10 6 metric tons/yr Possolan in PCC, lightweight 

aggregate, base stabiliza- 
tion, 1 EF 

CANMET production data. Production increasing rapidly, projection of up to 2.7 x 10 5 
metric tons/year by 1980. Currently produced in Nova Scotia, New Brunswick, Ontario, 
Manitoba, Saskatchewan, and Alberta. Uses generally covered by ASTM and CSA stand- 
ards. Significant research and development in progress: Portland-pozzolan cements, 
possolan specifications, and efficient lightweight aggregate production. Little fly 
ash now utilized (-90,000 metric tons /year) , most goes to disposal sites and/or 
landfill projects. Fuller utilization anticipated as markets developed. 

4. Steel slags 1.3 x 10 5 metric tons/yr Aggregate in AC ballast, 1 EF 

20 pet of 1975 steel ingot and casting production, less 50 pet recycle to flast 
furnace burden. Future production increases may be offset by increased recycling. 
Hamilton (Southern Ontario) major production and utilization area. Uses generally 
covered by local agency or owner specifications. (Since potentially expansive, care 
must be taken in EF.) Research in progress: skid resistance in AC and pavement 
design for steel slag AC. Little steel slag now used outside of works (-18,000 
metric tons/year in AC), in potential demand areas works' applications (EF) takes 
most. Much greater use in AC anticipated. 



142 

WASTE/BYPRODUCT PRODUCTION AMIN USES 

5. Demolition wastes 30.4 x 10 6 metric tons/yr Building demolition — timber, 

(including excava- lumber and bricks 

tion spoil) Excavation spoil — EF 

Old PCC — aggregate (base, PCC, 1 
AC 1 ), EF 

Old AC — aggregate (base, AC),EF 

Extension of Hamilton-Wentworth Region data, 1.32 metric tons/capita/year for all 
demolition, excavation, and construction wastes. Production increasing. Standards 
for various uses not explicitly developed, but often covered by ASTM and CSA stand- 
ards for conventional materials. Significant research and development in progress: 
recycling old PCC as aggregate in PCC and recycling AC. Except for mush use of 
excavation spoil in EF, most demolition waste goes to disposal sites and/or landfill 
projects. Significant recycling of AC is anticipated. 

6. Nickel and copper -1.9 x 10 6 metric tons/yr Aggregate in base construction 

slags ballast, EF 

Estimated from CANMET data and 1975 nickel and copper production. Production vari- 
able, depends on world nickel and copper demand. Sudbury major nickel slag produc- 
tion, and base construction and EF utilization area. Ballast hauled up to 800 km 
from production points. Uses generally covered by local agency or owner specifica- 
tions with some ASTM standards. Research in progress: cemented mine backfill using 
a cementitious blend of ground vitreous nonferrous slag (copper, nickel, lead, etc.) 
and PC. While ballast applications use a significant amount of current production, 
generally remote location of nickel and copper slags (and other nonferrous slags) 
has resulted in considerable stocks in addition to much of current production. More 
utilization may develop. 

7. Bottom ash =0.45 x 10 6 metric tons/yr Aggregate 1 (base, AC) EF 

Estimated from CANMET fly ash data, for powerplants only. Production increasing 
rapidly. Currently produced in Nova Scotia, New Brunswick, Manitoba, Saskatchewan, 
and Alberta. Standards for various uses not developed yet, but some local agency, 
owner, ASTM, and CSA specifications and standards applicable. Research in progress: 
applications in road construction, and influence of soluble sulfates. Except for 
small quantities used in demonstration projects and some EF, most bottom ash goes 
to disposal sites and/or landfill projects. Boiler slag, if separate from ash, is 
widely utilized. More utilization of bottom ash may develop. 



8. ^Cement kiln dust =0.45 x 10 6 metric tons/yr Filler, 1 EF 

Estimated from typical waste cement kiln dust production in Ontario and 1975 PC pro- 
duction. While production currently fairly static, large future increases antici- 
pated, particularly with trend to suspension preheater dry process plants (bypass 
dust). Production in all major urban areas. Use as filler and EF covered by local 
agency or owner specifications. Research in progress: filler in asphalt mixes and 
pozzolanic properties. (Much effort on other applications — fertilizer, waste treat- 
ment, absorption of S0 2 , etc.) Except for relatively small quantities used in EF, 
most waste cement kiln dust goes to disposal sites and/or landfill projects. More 
utilization, perhaps even full, will develop as more applications are demonstrated 
in construction and other applications. 



143 

WASTE/ BYPRODUCT PRODUCTION MAIN USES 

9. Bark and sawdust -50 pet of log volume Bark — recycling (pulp, particle 

(20 pet bark, 20 pet board, fibreboard, fluting 
sawdust, 60 pet chips) medium), roads 1 (frost protec- 
tion layer, lightweight fill, 
temporary construction, filter 
course) 

Sawdust and chips — recycling 
(pulp, particle board, fibre- 
board) , roads (same as for 
bark, main application is 
lightweight fill) 

For each log processed, about half the volume emerges as residues. However, amount 
not recycled or burnt during steam raising (or direct disposal that is decreasing) 
is very small proportion. Available quantities decreasing as recycling and fuel 
potential recognized. Lightweight fill applications covered by local agency special 
provisions. No known major research or development in progress. Lightweight fill 
applications use a very small quantity of wood wastes, and it is anticipated that 
full utilization within the wood industry will be reached. 

10a. Glass -1.2 x 10 6 metric tons/yr Aggregate 1 (base, AC) , terraco, 1 

bricks , 1 foamed and ceramic 
construction materials, 1 
light-reflecting road markings 

Estimated at 10 pet of municipal refuse (also estimate, 1975) . Does not include 
glass industry waste that is recycled directly. Production trends difficult to pre- 
dict as much pressure for more returnable containers, coupled with trend towards 
resource recovery from municipal and industrial refuse. Currently, little waste 
glass of suitable quality available for use in construction materials, but glass 
from resource recovery operations that is not recycled may become available in next 
few years. Standards for various uses not developed yet, but subject of ASTM com- 
mittee. No known major research or development in progress. (Significant research 
in past on AC containing waste glass.) Except for very small quantities collected 
or separated for demonstration projects, most waste glass goes to landfill sites as 
part of refuse or incinerator residues. Until resource recovery operations develop, 
little utilization anticipated and recycling will compete. 

10b. Iron mine over- 72 x 10 6 metric tons/yr Aggregate (base, PCC, AC), 

burden, cobbings, ballast, EF, filler, 1 roofing 

and tailings granules, brick manufacture 1 

Estimated from typical CANMET data and 1975 iron ore production. Production fairly 
static. As with most mining and quarrying wastes, very large stockpiles have built 
up. 14 iron mines in operation, mainly in remote areas of Ontario and Quebec. Uses 
generally covered by local agency or owner specifications with some CSA and ASTM 
standards. No known major research or development in progress. While use as 
aggregate in AC (traprock) , ballast, and roofing granules has involved fairly large 
quantities (particularly in Ontario) , transportation costs limit wide utilization. 
More utilization may develop . 



144 

WASTE/ BYPRODUCT PRODUCTION MAIN USES 

11. Tires 11 x 10 6 tires/yr Aggregate and/or binder compon- 

ent in AC 1 (roads and sport 
areas) 

Estimated from tire replacement data. Production increasing (also waste plastics 
and other rubber wastes) , but applications to capitalize on heat values (fuels and/or 
process steam) and chemistry may develop to require available production. Production 
in all areas. Standards for various uses not developed yet except in cases where 
natural materials replaced. Significant research and development in progress: cryo- 
genic processing and utilization in AC (Strain-relieving layers, binder, and 
aggregate). Except for small quantities used in demonstration projects, waste rubber 
not recycled goes to disposal sites. Increased utilization as construction materials 
not anticipated as recycling, fuel value, and recoverable components will offer 
strong competition for supply. 

12. Foundry sand Not known, probably EF, PC manufacture, 1 pipe 

greater than 1 x 10 6 bedding, backfill 
metric tons/yr 



Production data not available, but quantity probably decreasing as recycling becomes 
norm. Southern Ontario and Montreal area major production and EF utilization areas. 
Uses generally covered by local experience with some agency or owner specifications. 
Significant research and development in progress: use as kiln feed in PC manufacture 
and specifications for EF, bedding, backfill, etc., applications. At times, large 
quantities used in EF, but usually goes to disposal sites and/or landfill projects. 
More utilization should develop ♦ 

1 Potential use, technical feasibility demonstrated. 
AC - Asphaltic concrete. 

ASTM - American Society for Testing and Materials . 
CANMET - Canada Centre for Mineral and Energy Technology. 
CSA - Canadian Standards Association. 
EF - Engineered fill. 
PC - Portland cement. 
PCC - Portland cement concrete. 

References 

1. Benoit, E. The Coming Age of Shortages. Bull. Atomic Scientists, v. 32, No. 1, 

January 1976. 

2. Brooks, D. B. Conservation of Minerals: A Non-Renewable Resource. Ch. in 

Conservation in Canada, ed. by J. S. Maini and A. Carlisle. Canadian Forestry 
Service Pub. 1340, Ottawa, 1974. 

3. Hertzberg, P. A. (Study Director). Mineral Aggregate Study of the Central 

Ontario Planning Region, Ontario Ministry of Natural Resources, Toronto, 1974. 

4. National Academy of Sciences, Committee on Mineral Resources and the Environment. 

Mineral Resources and the Environment, Washington, D.C., 1974, 416 pp. 

5. Stussman, H. B. The Future's Materials. Eng. News-Record, v. 192, No. 18, 

Apr. 30, 1974, pp. 359-366. 



145 



POWERPLANT ASH UTILIZATION AND ENERGY CONSERVATION EFFECTS 

by 
J. H. Faber 1 



Versatility and availability give powerplant ash a tremendous edge over other 
byproducts in the battle for recycling supremacy. 

In fact, ashes are often effectively employed in combination with other indus- 
trial wastes, substandard aggregates, or standard materials to produce economical 
substitutes for more expensive natural aggregates, to reduce the environmental 
impact of disposal practices, to improve availability, and to reduce energy 
requirements . 

Being a residue of the burning process that transforms coal into electric power, 
ash has unique properties that require less energy in turning out acceptable con- 
struction materials and improving the quality of others in specific applications. 

Coal ash is firmly entrenched as the sixth most abundant mineral resource with 
the 1976 production amounting to 61.9 million tons. Last year's totals, being 
recorded as this paper is written, are expected to climb to about 65 million tons, 
and by 1985 the figure will be well in excess of 100 million tons . 

Blast furnace slags are listed in 10th position with availability totals in the 
area of 25 million tons annually. However, the quantities of many other wastes are 
not readily identifiable, principally because they are not presently in demand nor 
have they been researched, tested, and/or promoted. 

As a Nation, we are the most wasteful people on the face of the globe, but the 
time is rapidly approaching when we must take care of these materials and find use- 
ful applications for them or they will literally cover us up. 

In 1976, ash utilization reached an alltime high of 20 pet, or 12.4 million 
tons. The totals included 5.7 million tons of fly ash, 4.5 million tons of bottom 
ash, and 2.2 million tons of boiler slag. Early reports for 1977 indicate the over- 
all totals will be even higher. Predictions are that 15 million tons will find its 
way into the marketplace by 1980, thereby conserving the equivalent of 2 million 
tons of coal. 

Evidence that the overall tonnage will rise is significantly seen in a National 
Coal Association report that 259 new coal-fired electricity-generating stations are 
expected to be onstream by 1985. Many of these new plants are being sited to take 
advantage of developing western coalfields. 

An awareness and growing acceptance of ash as a viable construction material is 
expected to further impact this picture. Likewise, an industrywide movement toward 
dry handling, collection, and loading facilities should improve the marketability 
of ash by making greater quantities of ash readily accessible. Sluiced ash requires 
rehandling to prepare it for sale. 



L The author is with the National Ash Association, Washington, D.C. 



146 



RECYCLING METALS: PROCESSES AND ENERGY REQUIREMENTS 

by 

C. L. Kusik, 1 S. Malhotra, 1 M. Mounier, 1 
K. Parameswaran, * D. Kleinschmidt , 1 
and J. Milgrom 1 



Rather than produce new or "primary" metals from ores, substantially less 
energy might be used to recover and reuse the large quantities of scrap metals 
discarded each year by industry and householders. Since only general esti- 
mates of potential energy savings have been made in the past, this study was 
undertaken to gather data on U.S. energy requirements in 1976 for recycling 
nine metal commodities: iron and steel, aluminum, copper, zinc, lead, tita- 
nium, stainless steel, nickel and nickel alloys, and tin. Energy requirements 
for recycling prompt industrial (new) and obsolete (old) scrap metal have been 
estimated by major process routes, starting from the first collection center 
and ending with molten metal, ingots, or other semifinished forms roughly 
equivalent to a primary metal of similar composition. In addition, energy 
requirements were estimated for separating municipal solid wastes into four 
major fractions: Refuse-derived fuel, and magnetic, aluminum, and glass 
cullet fractions. 

In this study energy requirements for major methods of recycling were 
determined by process step. 

For each commodity being considered, typical processing schemes were 
selected for consideration based upon discussions with Bureau of Mines per- 
sonnel, consultants, Arthur D. Little specialists, the National Association 
of Recycling Industries, Inc., the American Iron and Steel Institute, the 
Institute of Scrap Iron and Steel, the Aluminum Association, and the Aluminum 
Recycling Association, as well as other trade organizations, and were con- 
firmed with plant personnel during field visits. For some commodities, only 
one sequence of process steps was selected since it was the only or predomi- 
nant recycling method, while for others several processes were included for 
detailed analysis. In addition, one municipal solid-waste flowsheet was 
selected for analysis to indicate the potential for recovering the components 
of raw refuse in a form suitable for recycling into the economy. 

Scrap metals are normally classified into three categories: Home scrap, 
prompt industrial scrap, and obsolete scrap. Home scrap is generated within 
the smelting or refining facility and is recycled directly back into the melt- 
ing furnaces. Prompt industrial scrap is normally generated within manufactur- 
ing operations and is recycled back to the smelting and refining facilities, 
which may be located some distance from the manufacturing facilities (for 
example, scrap generated during the manufacture of automobiles or scrap gener- 
ated in lead battery manufacturing operations) . Obsolete scrap (or post- 
consumer scrap) is old scrap generated at the end of the products' life cycles. 



All of the authors are with A. D. Little, Inc., Cambridge, Mass. 



147 



Use of the term "new materials" can refer to either new scrap (prompt 
industrial scrap) or new materials derived largely from ore. To avoid such 
ambiguity, we have attempted to restrict our terminology, referring to new 
scrap as prompt industrial scrap and referring to commodities largely derived 
from ore as virgin materials. This study considered only the prompt indus- 
trial and obsolete scrap generated and recycled in 1976. Home scrap use, 
however, has been identified if it is a typical part of the processing 
sequence. 

As a raw material, scrap is assigned a zero energy content in this analy- 
sis. Scrap used as a flux, such as iron units introduced to a secondary lead 
blast furnace, is charged with an energy value approximately equivalent to 
producing the commodity from virgin raw materials. Table 1 shows energy 
values for fuels, other energy sources, and transportation which were derived 
from previous work done for the Bureau of Mines by Battelle Columbus 
Laboratories. 

TABLE 1. - Energy values used for fuels and energy sources 

and modes of transportation 



Energy value 



Modes of transport: 

Truck million Btu per net ton-mile transported 1 . 

Rail do. 1 

Water do . 1 

Fuels and energy sources: 

Anthracite coal million Btu per net ton. 

Bituminous coal do 

Metallurgical coke do 

Distillate fuel oil Btu per gallon. 

Residual fuel oil do 

Natural gas Btu per cubic foot . 

Electricity Btu per kilowatt-hour 2 . 

Steam, low-pressure (per 1,000 pounds steam) million Btu. 

Steam, at 100 psig (per 1,000 pounds steam) do 



0.0024 
0.00067 
0.00025 

25.4 

25.0 

31.5 

139,000 

150,000 

1,000 

10,500 

1.0 

1.4 



1 1 net ton = 1 short ton = 2,000 pounds. 

2 Based on approximate fossil fuel equivalent used to generate 1 kilowatt -hour. 



Similarly, the energy requirements for materials consumed in recycling 
(fluxes, oxygen, refractories, etc.) were included in this analysis. In each 
of the recycling schemes, a transportation distance estimate was made. Such 
estimates were based upon field visits and industry personnel. 

In addition, pollution control, in-plant transportation, and space heat- 
ing energy use are included in the values reported here. 



For the metals considered, amounts of scrap recycled in 1976 are shown 
in table 2. Potential recovery from municipal solid waste is shown in table 3 
It is seen that the potential annual recovery of steel scrap and aluminum 
scrap from municipal solid waste is roughly equivalent to the new scrap 
generated. 



148 



TABLE 2. - Amount of scrap recycled in 1976, thousand tons 



New' 



01d ; 



Total 



Aluminum 

Copper 

Iron and steel 

Lead 

Nickel and nickel alloys 

Stainless steel 

Tin 

Titanium , 

Zinc , 



1,030.0 

940.0 

!2, 629.0 

100.0 

34.5 

208.0 

7.7 

8.4 

128.0 



416 

485.0 

18,515.0 

570.0 

23.0 

171.0 

10.5 

.4 

52.0 



1,446.0 

1,425.0 

41,144.0 

670.0 

57.5 

379.0 

18.2 

8.8 

180.0 



Figures are for scrap consumption unless otherwise indicated. 

Prompt industrial. 
3 0bsolete. 
4 Amount of scrap received. 

Sources: Bureau of Mines and Arthur D. Little, Inc., estimates. 

TABLE 3. - Potential for recovery from municipal solid waste 

(Basis: 200 million tons per year refuse-derived fuel 
from municipal solid waste) 



Magnetic fraction (largely iron and steel) . .million tons per year.. 

Aluminum do 

Glass cullet do 

Refuse-derived fuel at 7 , 000 Btu/lb Btu. . 



20 

1 

1 

2.8 x 10 15 



Table 4 shows energy requirements for preparation of the scrap metals 
considered in this study. After preparation, a mix of the prepared scrap is 
generally charged to various melting and/or refining furnaces to produce a 
semifinished product. Energy requirements for scrap preparation as well as 
for melting and refining are summarized in table 5. 

Since very few commercial municipal solid waste (MSW) resource recovery 
facilities were in operation in 1976, no processing scheme can be considered 

typical" in this relatively new technology sector. Recognizing that good 
energy data are generally lacking for the large number of processes being 
proposed, only one system was chosen for analysis. It was recognized that 
this would indicate only an order of magnitude of energy use, since a more 
definitive energy study would have to await commercial implementation of the 
technologies involved on a wider scale. 

For the purposes of this study, the Bureau of Mines resource recovery 
flowsheet has been used. Although no commercial installations utilized the 
process in 1976, many processes have included portions of the technology and 
several installations in the planning stage or under construction intend to 
use a large portion of the process. A commercial-scale process much like the 
one described is under construction in Rochester, N.Y. Design capacity is 



149 



2,000 tons of MSW per day. The energy estimates presented in this analysis 
are not meant to be representative of current industrial practice. They 
represent an estimate of the energy that would be consumed by an installation 
based on the Bureau of Mines flowsheet . Estimate of energy requirements for 
treating municipal solid waste (MSW) to recover 1 ton of refuse-derived fuel 
(RDF) associated with recovery of 205 pounds of magnetic scrap, 187 pounds of 
glass cullet, and 11 pounds of aluminum scrap is about 0.66 million Btu to 
recover the above mix of segregated scrap fractions . 



TABLE 4 . - Energy requirements for scrap preparation 
(including scrap transportation) 



Commodity 



Scrap preparation process 

Clippings by baling and/or shredding 

Borings and turnings by shredding 

Aluminum drosses by milling and/or dry 
screening. 

Sweating of high- iron scrap , 

Sheet and cast scrap by shredding , 

Wire by chopping , 

Wire by incineration 

Automotive scrap by shredding , 

Automotive scrap by guillotine shearing 

Ferrous scrap by baling 

Ferrous scrap by alligator shearing 

Ferrous scrap by torch cutting 

Home scrap by torch cutting 

Crushing of borings and/or turnings , 

Battery breaking 

General lead scrap 

Crushing of turnings 

Preparation of solids 

Shredding of turnings 

Baling of light scrap 

Torch cutting and/or shearing of heavy scrap 

Alkaline leaching of prompt industrial 
tinplate. 

Light scrap by crushing 

Heavy scrap by cutting, caustic cleaning, 
acid pickling . 

Dross and/or skimming collection 

Sweating auto die-cast scrap 

Sweating mixed die-cast scrap « 



Million Btu 
per ton of 
prepared scrap 



Aluminum . 



Copper, 



Iron and steel 



Lead, 



Nickel alloys . . 



Stainless steel 



Detinned steel. 



Titanium. 



Zinc 



0.91 
3.05 
1.06 

9.28 
1.18 

1.75 
1.67 

1.28 
.65 
.72 
.47 
.34 
.02 
.75 

.62 
.24 

4.02 
2.46 

1.93 

1.13 

.98 

2.02 



3.98 
4.14 

.24 
4.00 
2.10 



150 



TABLE 5, - Summary of energy requirements by commodity and process in 
secondary metal recycling including scrap preparation 



Commodity and/or process 



Product 



Million Btu 
per ton of 
product 



Aluminum : 

Reverberatory melting aluminum scrap 
Do 

Reverberatory melting aluminum cans. 
Copper: 

Reverberatory melting No. 1 copper 
scrap . 

Anode furnace and/or electrolytic 
refining No . 2 copper scrap . 

Cupola, converter, and/or electro- 
lytic refining low-grade copper 
scrap. 

Reverberatory melting brass and/or 
bronze scrap . 
Iron and Steel: 

Electric arc furnace 



Ingots (casting alloys) . . . 
Hot metal (casting alloys) 
Hot metal (can stock) 



Wirebar , 



,do 
.do. 



Brass or bronze ingots 



Cupola 

Lead: 

Pot melting , , 

Blast furnace alone (hard lead) ..... 
Blast furnace-reverberatory furnace 
combination: 

Hard lead from blast furnace , 

Soft lead from reverberatory 
furnace . 
Nickel alloys : 

Induction melting (double vacuum) . . , 

Air induction melting 

Stainless steel: Argon-oxygen- 

decarburization (AOD) . 
Tin: Tin recovery from detinning 
leach solution by electrowinning. 
Titanium: Vacuum arc furnaces 

(double melting) . 
Zinc: 

Distillation retorts 

Muffle furnaces 

Do 

Do „ ...!!!"!!! 

Pot melting clean diecastings 

Pot melting off-specification 
diecastings. 

4*17 million Btu is accounted for by 
The scrap-to-sponge ratio affects the 



Continuously cast blooms 

and/or billets. 
Castings 



Ingots 



.do. 



.do. 
■ do. 



.do 
.do. 



Strand-cast billets 
Electrolytic tin.... 



Zinc dust. . 
Slab zinc. 
Zinc dust. . 
Zinc oxide. 
Cast alloys 



.do 



15.06 

19.60 

8.72 

3.81 

17.27 

42.42 

7.09 

8.33 
x 31.67 

.61 

9.65 



9.61 
8.05 



19.45 

11.08 

9.69 

172.88 
( 2 ) 



24.01 
18.93 
19.71 
19.71 
2.58 
3.26 



.18 ton of pig iron per ton of castings, 
total energy required. 



151 



BUREAU DE RECHERCHES GEOLOGIQUES ET MINIERES 

PROCESSES FOR RESOURCE RECOVERY 
FROM FRENCH URBAN WASTE 

by 

J. N. Gony 1 and F. Clin 1 



Nowadays, the French industry is relying for nonenergetic supplies 
(excluding building materials) on national resources for 15 pet and on recy- 
cling for 30 pet; the remainder is imported. 

It is in a like manner that, in 1974, a trade deficit of more than 
8 billion francs resulted, for an overall deficit of 16 billion francs 
(table 1). 

However, during the same year, local communities had to assume the 
elimination of more than 12 million tons of urban waste, consisting of 
approximately as much paper and cardboard as imported, as much tin as 
recycled, and amounts of glass, polyvinyl chloride, and polyethylene much 
greater than presently recovered . 

Moreover, the energetic content of all these materials represents 5 pet 
of the fuel equivalent consumption of French industry, 80 pet of which could 
have been saved by recycling (table 2) . 

It is in such a context that the Bureau de Recherches Geologiques et 
Minieres (BRGM) has stepped in. Well aware of the needs and means of French 
local communities, it has therefore studied 

1. For the largest towns where incineration is the usual mode of elimi- 
nation, the recovery of the components in the resulting residues, 

2. For average size communities, the sorting and benef iciation of raw 
household refuse, and 

3. For smaller agglomerations, the sorting of segregated products. 

In the field of household refuse sorting and recovery, the BRGM has, 
therefore, acquired a set of new techniques offering various solutions to the 
present-day problems of waste elimination and shortages of nonenergetic 
resources (fig. 1). It offers better prospects to the local communities 
concerned, as the case may require, and contributes to bring about a more 
favorable balance in the global materials supplies for France in the near 
future. 

_ p «; 

1 Both of the authors are with the Bureau de Recherches Geologiques et Minieres, 
Orleans , France . 



152 



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154 



Ungraded 
material 



Fixed 
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+ 



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Hammer 
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_Magnetic 
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Vibrating 
" screen 



t 
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Fine 
i meta Is 

/ \ 
M NM 



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t r- 

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Bulky Coarse 
items nonferrous 
metals 



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iron 

scrap 



Pump 



Filter 
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+ Oversize 
- Undersize 



Solid flow 
Water flow 



M Magnetic 
NM Nonmagnetic 



M NM 

Fine 
slag 



FIGURE 1. - Bureau de Recherches Geologiques et Minieres process flowsheet for incineration 
residues beneficiation. 



155 



WASTE PRODUCTS TO FERTILE SOIL—THE COMBINATION OF FLUE GAS DESULFURIZATION 
SLUDGES AND FINE COAL REFUSE WITH MUNICIPAL WASTE 



by 
R. C. Freas 1 and R. W. Briggs 1 



Flue-gas desulfurization sludges (FGD) are the byproduct of the scrubbing 
process used to reduce or eliminate sulfur dioxide emissions at coal-fired 
electricity-generating stations. Scrubber sludges consist of calcium sulfate 
and calcium sulfite salts, have a pastelike consistency, low shear strength, 
and bearing capacity, and are thixotropic. In addition to the calcium 
sulfite-sulfate reaction products of scrubbing, the solid phase includes 
various amounts of fly ash and unused scrubbing reagents. The aqueous-phase 
chemistry varies depending upon the soluble and volatile components of the 
coal, the scrubbing process chemistry, evaporation, and other concentrating 
effects during scrubbing. 

Coal fine refuse is the minus 28-mesh product of coal cleaning and 
possesses many of the same physical properties attributed to FGD sludges. 
Traditionally, it has been handled either as a slurry to be disposed of in 
refuse ponds or behind an embankment, or it has been formed into a filter 
cake and transported to some form of a landfill. Both disposal methods are 
now under close scrutiny by Federal and State officials, and it appears that 
alternate forms of disposal will have to be found if environmental criteria 
are to be met. 

Thus, it was that Drave Lime Co., with the support of the U.S. Environ- 
mental Protection Agency, Project No. F803999-01-0, undertook a research 
project aimed at developing fertile soils from the combination, stabilization, 
and disposal of flue-gas desulfurization sludges, coal fine refuse, and muni- 
cipal waste. 

Municipal sludge is the byproduct of municipal sewage treatment and has 
been a continuing problem for most sanitation districts . One of the primary 
problems in utilizing waste activated sludge in a combined disposal mode with 
other waste materials is the extremely low solids content, which consequently 
results in a very high water contribution to the combined waste products. 
Since these low solids contents, 0.7 to 8.0 pet solids by weight, were felt 
to be undesirable, the investigation was restricted to municipal waste filter 
cake, 17.5 to 25 pet solids by weight. 

The pot growth tests with both the FGD sludges and the coal fine refuse 
demonstrated that the test mixtures would support plant growth. Nevertheless, 
there was considerable variation in the rates of plant growth between the 
species used. Ryegrass was the first plant type to germinate, followed by 
soybeans and then oats. From the comparison of the growth rates, germination 

1 Both of the authors are with the Drave Lime Co., Pittsburgh, Pa. 



156 



data, and the plant descriptions, and the soil and plant chemistry, table 1, 
it is apparent that the plant species employed in the growth tests is of 
nearly equal importance with the mixture itself. In other words, plant toler- 
ance will affect the success of any seeding done on a synthetic soil resulting 
from a combination of waste materials. 

TABLE 1. - Summary of element occurrence compared with recommended ranges 



Element 



Potassium. 
Calcium. . . 
Zinc 



Copper. . . . 
Manganese, 



Iron. 



Aluminum 

Phosphorus. . . . 



Crownvetch 



Normal 

do 

Excessive 1 . . 



Low 
Normal , 



Normal to high 



Excessive 

Normal to low, 



Corn 



Normal 
...do. 



. . .do . 
Low . . . 
Low . . . 



Normal . . . 

Excessive 
Deficient 



Oats 



Normal . . . . 
do 

Low to 
deficient, 
.... do .... 



Normal , 



Normal to 
excessive, 

• • • • uU • • • • i 

Very 
deficient, 



Soybeans 



Low 

Normal 

• • • • CL(J • • • • • 

Low to 

deficient. 
Normal to 

low. 
Normal to 

high. 

• • • • CJ.L) • • • • • 

Very 
deficient. 



Ryegrass 



Normal . 

Do. 
Low. 

Low. 

Normal . 

Normal to 
high. 
Do. 
Low. 



1 Crownvetch plants were started in their own potting so 
to the project where they were then transplanted to 
The potting soils were high in zinc, and, therefore, 
them are high in zinc. 



il and were delivered 
the artificial soils, 
the plants started in 



Chemical analyses were completed on the plant materials harvested from 
the outdoor test plots in order to determine those elements that were present 
in either deficient or toxic quantities. Table 1 summarizes the results of 
testing for some of the more important elements in relation to their desired 
level of occurrence. In general, since all of the prepared soil materials 
were deficient in phosphorus, the plants were also phosphorus deficient. 
Because of the high pH of the parent materials, most of the plant materials 
had high to excessive levels of aluminum and iron, while the availabilities 
of heavy metals were maintained at low levels . 

Thus, it was concluded that the high pH of the prepared soils used in 
this study would reduce the availabilities of high metals in acid materials 
if they were mixed with the artificial soil. This then would indicate that 
the FGD-municipal sludge mixtures and/or the FGD sludges alone represent a 
potential for mixing with acid mine spoils and in strip mine reclamation. 

Permeability rates averaged a very low 5.3 x 10~ 5 cm/sec; nevertheless, 
leachate samples were collected, when available, and were subjected to chemi- 
cal analysis. Fourteen major constituents were tested for, all of which 
proved to be present in quantities that were below critical environmental 
levels (table 1). However, the pH values and sulfate (SO^) ion concentrations 
were relatively high owing to the fact that the FGD sludges were derived from 
a high-sulfur environment. Because of the low permeabilities of the stabi- 
lized sludges, the relatively low volumes of leachates that would be generated, 



157 



and the overall leachate quality, it was felt that the potential for signifi- 
cant ground water quality deterioration resulting from the use of these 
stabilized materials was minimal. 

The coal fine refuse-municipal waste test mixtures and the coal refuse 
alone were very successfully stabilized. In addition, it was possible to 
germinate and grow several plant varieties, although the stabilized test 
mixtures were droughty and subject to high plant mortality if not watered 
regularly. Nevertheless, when stabilized, the fine refuse could be handled 
with conventional landfill methods and had very low permeability rates . 
Additional plant material work remains to be done with these soils if their 
full fertility potential is to be realized. 

From the comparison of the plant growth rates, germination data, and 
plant descriptions, it is apparent that the species of plant selected for 
growth testing bears significantly on any results achieved. Therefore, it 
was concluded that additional testing is needed with plants specifically 
selected for their salt and high pH tolerances. Since plants vary consider- 
ably in their ability to accumulate various elements, a wide array of species 
will have to be tested in order to fully evaluate the potential of the 
several sample mixes as fertile soils. Nevertheless, this investigation 
did demonstrate that the selected waste materials could be combined and 
stabilized to provide a synthetic soil material that would support plant 
growth . 



-MJ.S. GOVERNMENT PRINTING OFFICE: 1980-603-102/69 int.-bu.of mines.,pa. 24719 



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